The remarks, the first direct response by Ayatollah Ali Khamenei, came as Iran's government again urged Saudi Arabia to be wary over the plot claims that Iranian officials tried to contract a Mexican drug cartel to kill the Saudi ambassador to Washington.
The US government is rallying other nations to its bid to further isolate Iran over the plot and has provided allies with details it says prove the outlandish assassination bid was genuine.
US President Barack Obama on Thursday warned Iran would be held to account over the alleged plot, which he described as part of a pattern of "dangerous and reckless" behaviour by Tehran.
Iran's strenuous denials of involvement, made ever since the alleged plot was made public Tuesday, were capped Saturday with Khamenei's speech.
"It's a meaningless and absurd accusation regarding a number of Iranians," he said in a speech carried by state television.
"But it has not stuck and it will not stick," he said.
Khamenei added defiantly: "They say that they want to isolate Iran. They are the ones who are isolated."
US officials admit they do not know which of Iran's leaders, if any, are implicated.
But Obama stressed that "even if at the highest levels there was not detailed operational knowledge, there has to be accountability with respect to anybody in the Iranian government engaging in this kind of activity."
The US Justice Department and FBI say the trail leads to officials inside the Quds Force, a special operations outfit within Iran's elite Revolutionary Guards.
Quds Force personnel are said to have transferred nearly $100,000 to the bank account used by a member of a Mexican drug cartel who was really a paid US informant who tipped off the FBI.
The money was allegedly a down payment for a $1.5-million-dollar hit on the Saudi ambassador, Adel al-Jubeir, possibly through the bombing of a Washington restaurant.
An Iranian used-car salesman who is a naturalised US citizen living in Texas, Manssor Arbabsiar, is said to have confessed to acting as the go-between for his cousin, whom he described as a high-ranking official in the Quds Force, and the Mexican cartel.
Arbabsiar is in US custody, charged with the plot.
The US Justice Department has also charged another Iranian identified as Gholam Shakuri, who is said to be an Iran-based Quds Force operative who flew to the United States to speak with Ababsiar. Shakuri is now believed to be in Iran.
Saudi Foreign Minister Prince Saud al-Faisal has said his country "will find a suitable response" against Iran for the alleged plot.
But Iran's foreign minister, Ali Akbar Salehi, on Saturday said: "We hope the Saudis will deal with this issue with caution."
He accused the United States of trying to create divisions in the Middle East but said "Saudis were too wise to get involved in this political game," according to the Fars news agency, citing comments Salehi made on state radio.
Initial US actions following the alleged plot revelation seem to be focused on adding to US and UN sanctions already imposed on Iran over its controversial nuclear programme.
A US Defence Department spokesman on Wednesday downplayed the possibility of US military action against Iran, though he said the final decision rests with Obama.
While the US president has said "we don't take any options off the table in terms of how we deal with Iran," he suggested increased economic, political and diplomatic pressure would be the tools used.
Sanctions experts, including former US Treasury Department officials, say that successive rounds of sanctions have left only a few big targets.
If they were subject to US or multilateral restrictions, it could have devastating effects on Iran's economy, and its population of 75 million.
At the pinnacle of the target list is the Central Bank of Iran, or Bank Markazi, which sits at the centre of Iran's financial and energy interests.
While the US government already bans its citizens and entities from doing business with Bank Markazi, convincing Europe to join in could profoundly reduce government revenues and destabilise Iran's currency, say experts such as Avi Jorisch, a former advisor at the Treasury Department's office of terrorism and financial intelligence.
"Iran handles its oil business through the central bank," said Jorisch.
Oil sales account for 80% of Iran's foreign exchange revenue, and if the Iranian currency were laid low, Iranian civilians could find it very difficult to buy imported food and medicine.
There are other risks for Washington in such a move.
Choking off Iran's ability to sell oil in Europe, India or Japan, without pumping more from the likes of Saudi Arabia, could also result in significantly higher oil prices in the United States and Europe.
COMMENTS (25)
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@Lal Bahadur: And Arab nations are doing much better! The rich keep the wealth in the family while the rest of the country rots in its own poverty. The Middle East needs to stop living in the caste era and step into modern day democracy, start taxing the rich and pay their part to the rest of the world who made them rich in the first place.
This has recently been observed in Karachi Pakistani court, that Minor orphan children are adapted by Christians, NGO's who, latter on are sent abroad to, kids to Africa, boys are raised with special skills in crimes and suicidal attacks and the girls for prostitution.If caught and tested their DNA test, match with that of Asian countries, countries who are on the hit list. If CIA., is so sure, why not they take extra care for those who are to be targeted. This mean CIA, pursue such game, and respond when crime take place. These nasty activities are done under the nose of Freemason group who have criminal record.
@ James Watt your are streaching it This has nothing to do with one beliefs, This Man is simply speaking the truth......period.
@James Watt: Don'y manipulate the whole idea of peace and brotherhood my bro...to tell the truth, u dnt hv to be a Shia or Sunni...!!
Iran is a country of Shias, and they never lie nor disrespect other religions.
There's no smoke without fire. The allegation wasn't unfounded, given the price the U.S. would have to pay, were it not true. Of course Al Khamenei as the supreme leader of Iran has to dismiss it, even if some elements within the Revolution Guard could have planned this plot on the own to undermine the executive power, taking advantage of the schisms between Ahmadinejad and Al Khamenei.
@ Brandon, What is crumbling is the Amercian and the European Union Economy.
A simple statement by Ali Khamanie of Iran is more believable then the storm the western media is trying to create against Iran, Simply because Iran dosent invade a country on manufactuured lies. Good story for a Walt Disney production
I can see bunch of CIA operatives throwing Cow pies on the wall hoping that out of all some will stick against Iran and they will get their lucky break, Sorry this one didnt, It may well be easy to convince tthe europeans but Asia is a different ball game.
Just Like Faisal Masood case in NYC and AAfia Siddique case and ........and...... and...
Its just a game of US to make the situation more worst for Iran...and shame on Saudi Arabia that they are blind followers of US. they should realize now that US is using them against a Muslim country as Sadam was used before.Whats the reason for killing Saudi ambassador..
Well... http://www.dawn.com/2011/10/12/evidence-of-iranian-plot-overwhelming-prince-turki.html
I'm reminded of the immortal words of Mandy Davies in 1956, : "Well, he would say so wouldn't he?"
(Mandy Rice-Davies was the courtesan who brought about the downfall of the British defense minister, John Profumo, and said when a reporter asked about Profumo's denial of sharing her with a Russian agen.)
Haj starts in couple of weeks, America has planned this occasion to get the two important states in middle east against each other. Obama is looking for next term election, this is a golden chance for america to play the game.
what about the arab royals working with usa and uk to assassinate iranian president which wikki leaks exposed?
Ayatollah of truth has spoken. FBI should listen.
CIA first find the reported bomb Made by Iraq
Khamenei says America's claims are absurd?
America says Khamenei's entire worldview is absurd.
Which proves the world's point.
Saudi Arab and Iran have long term enemity for 'obvious' reasons. But Killing-plot of a diplomat is shameful act of Iranians.
The alleged iranian plot is one of the many outcomes from CIA's "institute of terror plot engineering". We must recognise CIA's effort on designing & devoloping such plots but this plot wasn't planned out well & thus failed to fool the world. Guess the stress from being pounded in AF really got to them & impaired their thinking capability. Hope Iran doesn't go too hard on them in iraq. Mr. Ayatollah Ali Khamenei please don't go too hard on mentally impaired people they are innocent like little babies.
Not having great success of public pressure against Pakistan, US tries and uses its think tank against Iran to pressurize it! US just can not sit easy and not let the world know that it is the super power of world.
The accused was actually talking to a DEA agent when he was trying to arrange the assassination - no doubt these conversations were recorded and no doubt Iran will deny even after the accused pleads guilty in court.