Rouhani stopped short of saying who had used the arms - Tehran has previously accused Syrian rebels of being behind what it called suspected chemical attacks.
He also did not mention the international furore around Syrian opposition reports that forces loyal to the Damascus government killed as many as 1,000 civilians with poison gas in suburbs of Damascus on Wednesday.
"Many of the innocent people of Syria have been injured and martyred by chemical agents and this is unfortunate," recently elected Rouhani was quoted as saying by the ISNA news agency.
"We completely and strongly condemn the use of chemical weapons," he said, according to the agency.
"The Islamic Republic gives notice to the international community to use all its might to prevent the use of these weapons anywhere in the world, especially in Syria," he added, according to the Mehr news agency.
Syria's government denies using such weapons and Iran's foreign minister earlier this week said groups fighting Syrian president Bashar al Assad in a two-year-old rebellion must have been behind what he then said was just a suspected attack.
Russia, another major ally in the Syrian government, has also blamed opposition forces.
Syria's uprising against four decades of Assad family rule has turned into a civil war that has killed more than 100,000 people.
Foreign powers have said chemical weapons could change the calculus in terms of intervention and are urging the Syrian government to allow a UN team of experts to examine the site of Wednesday's reported attacks.
The United States on Friday was repositioning naval forces in the Mediterranean to give President Barack Obama the option for an armed strike on Syria, although officials cautioned that Obama had made no decision on military action.
COMMENTS (4)
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@John B: Being an american muslim i totally agree with you. on the other hand if any side has used some kind of a chemical weapon it is totally wrong. Even this doesn't give america the right to intervene and at worse attack syria. Let UN handle it.
How can a government use chemical weapons against citizens no matter how cruel it can be? So Saddam Hussain considered Kurds as non-citizens. And per your opinion it is OK to use chemical weapons against non-citizens.
As an American it is my opinion that the US does not understand the dynamics of Syrian quagmire and supporting the rebels is a wrong move for peace in the region.
As far as who used the chemical weapons and where did it come from, one can safely say if they were used by the rebels it is from Libya cache and Syrian govt must be idiotic to use them when all barrels against it are pointing towards Damascus.
Syria has become a proxy war against Iran now, although that was not how it was started.
Various interest groups, such as Saudi, the US, Israel, and their allies, and Sunni islamists camps on one side and the opposite camps such as Iran, Russia and others on the other side now do not know how to stop the wheel set in motion essentially by the Sunni islamist jihadis who have a well orchestrated plan to capitalize an event of civil unrest from Tunisia to Syria.
My fear is this low intensity war in this region will blow into a big scale, as it has always been so in the history.
The last straw that will turn the region into a full-scale war with global calamity will be any skirmishes against Saudi Arabia or Israel or Turkey.
Who is creating the problem and fighting in the rebel force? In my view: Sunni Islamist jihadis of caliphate dream aided my the mercenaries organized by syrian muslim brother hood. Who are supporting them. Everyone since their interests are conflicting.
I prefer the US to stay out of the quagmire and keep a watch and not get sucked into the ploy being played by the rebels. Too many actors on each side now and any miscalculation from each side will be beyond the control of anyone.
Syrian unrest will end if Egypt is settled.
The standard accusation of the US and Israel in creating problem in Syria, although appealing to many, is without any merit since unrest in the region is against the US and Israel interest.