Clinton commended India for lowering its purchases but called for more as a deadline looms for the United States to slap sanctions on nations that still buy Tehran's oil.
"We hope they will do even more and we think there is an adequate supply (from other exporters) in the market place," Clinton told a forum in Calcutta before she met Prime Minister Manmohan Singh in New Delhi.
"We think this is part of India's role in the international community."
India, which depended on Iran for 12 percent of its imports last year, says it has cut Iranian imports "substantially" despite initially insisting it would not join US and European-led efforts to cut off Tehran's oil revenues.
Faced with critical questions from students, Clinton stressed that the United States had no quarrel with the Iranian people and voiced hope for a peaceful solution, with new talks coming up between Iran and major powers.
But Clinton called the prospect of a nuclear-armed Iran "the principal threat" and said that US ally Israel - which has its own undeclared nuclear arsenal - had legitimate worries.
"This is a regime that has a history of aggressive behaviour and I don't think you deal with aggressors by giving in to them," Clinton said.
"I think that Israel is very worried that if Iran were to get a nuclear weapon, there might be a decision by some future leader and that would be devastating," Clinton said before she flew to New Delhi.
Iran says that its uranium work is for peaceful purposes and US intelligence has not concluded that Tehran is developing a nuclear bomb, with many experts believing the regime is most concerned with its own survival.
India has historically had warm relations with Iran and has been more concerned by Pakistan, where the purported mastermind of the 2008 Mumbai attacks - Hafiz Saeed - lives openly.
Clinton pledged to keep up pressure over Saeed, for whom the US has offered a $10 million reward for information leading to a conviction.
She also said she believed Egyptian cleric Ayman alZawahiri, who took the helm of al Qaeda after US forces killed Osama bin Laden a year ago, was hiding in Pakistan, which has a longstanding but rocky partnership with Washington.
Clinton paid the first visit by a senior US official to Calcutta in hopes of reaching out to a fellow female leader, West Bengal's Chief Minister Mamata Banerjee.
Clinton asked Banerjee to support opening up India's retail sector to foreign giants such as Walmart, which are eager to break into the potential market of 1.2 billion people.
Banerjee's party blocked the reform in parliament, amid fierce opposition by owners of India's omnipresent small shops who fear they would not be able to compete.
The world's two largest democracies have rapidly expanded ties since overcoming mutual mistrust during the Cold War, but tension over Iran and difficulties in their trade relations have stunted progress.
Relations between Delhi and Washington were reset by former US president Bill Clinton in the 1990s and invigorated by his successor George W Bush, who signed a landmark nuclear energy deal that was meant to hand business to US companies.
Legislation passed in India since then is seen by Washington as penalising privately-owned US nuclear companies, which are unable to take on the liability imposed on them in the event of an accident.
State-backed firms from France and Russia have profited at their expense.
"We've made it clear to the government that under the legislation that was passed it would be difficult for US companies to participate," Clinton said. "We are still discussing this and we're hoping there will be a way to work out the remaining kinks in this."
While critics say US-India relations are drifting, US officials point to growing trade and friendly relations between the two nations.
Clinton tried to use a personal touch to reach out to the Indian people. She told the audience in Calcutta that she and Bill Clinton related to Indians in part because of the country's celebrated culture of debate.
"My husband and I have just such a great personal affection for India - maybe because we're a little argumentative ourselves," she said.
COMMENTS (13)
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I advise you Mrs. Hilary Clinton please don't waste your time in this regard because your all efforts are in vain,useless and impossible to stop India to import oil from Iran.
As I see it, this Iran crisis will actually work in India's favor. The present Iran crisis will not be over for another five years and as for oil import India might as well get a part of the deal in waiver and part of the deal with Saudi and Kuwait with domestic rupee purchase in lieu of Iranian purchase.
Actually, India will be the one that will bring Iran to the table as she did with Burma and there is more to the story than curtailing Iranian oil import.
Total Iranian oil curtail by India will not be possible and US cannot justify why EU and Japan who together purchase more than 12% of Iranian oil are waived whereas India must comply. India domestic politics might not allow any political parties to make this a palatable deal unless the same reciprocal offers in India's favor are on the table and Clinton knows that as well. So in this crisis Indians will come out unscathed with better long term offers from Saudi and Kuwait than what they have presently with them.
US cant slap sanctions on India.....ultimately US will grant waiver to India claiming that India cut down its oil imports from iran...in reality India-Iran trade, which is now in rupees, will go as usual.....We are no pakistan.....:P
@Paras Vikmani: then they put section on india.this is the beganing of a partnership,they would like India to do all there dirty worke for them.
India must follow an independent foreign policy, The enemy of a friend is not necessarily my enemy.
Wisdom is the better part of valour in this case
The USA believes that sanctions against Iran are the best chance to avoid a full out war - that's why it's pressing everyone to get on board. India will either comply or it's going to discover just how much it's economy is driven by the USA. A peaceful resolution to the Iran conflict is in everyone's best interest.
@Ali Wali: India has a trade deficit with most major trading nations except USA (and the UK).
@Ali Wali: Actually India has trade surplus with US
India must not bow to US pressure in reducing oil imports from Iran