The UN nuclear watchdog (IAEA) has passed a resolution censuring Iran over its nuclear programme but stopped short of recommending sanctions.
Iran says its nuclear programme is to meet energy needs only
The vote follows a compromise deal between the US and Europe over how tough to be with the Iranians.
Washington had insisted any breaches by Iran should go to the UN Security Council, which has powers to sanction.
But under the new deal, any violations will be referred to the International Atomic Energy Agency instead.
The resolution "welcomes Iran's offer of cooperation and openness" but also "strongly deplores" Tehran's past cover-up of its nuclear activities and calls for a "particularly robust verification system" .
It warns against "further serious Iranian failures", saying that could lead the IAEA to consider all options at its disposal - shorthand, correspondents say, for Security Council action.
US Secretary of State Colin Powell said on Tuesday that Washington was very satisfied with the wording of the resolution.
"There is one particular paragraph in the resolution which makes it very, very clear that if Iran does not now comply with obligations and the other agreements it's entered into, then this will be a matter that will be immediately referred to the IAEA board of governors for action," Mr Powell said in Washington.
But Iran also put a positive spin on developments.
"This resolution was an achievement for Iran and proved that
Iran has followed its peaceful nuclear activities with
transparency and truthfulness and that despite all the fuss made
by some arrogant circles it was not trying to produce and obtain
nuclear arms," Foreign Ministry spokesman Hamid Reza Asefi said
in a statement faxed to Reuters news agency.
Speaking before the meeting, Iran's ambassador to the IAEA, Ali Akbar Salehi, said Iran stood by its commitment to sign up to an accord on tougher inspections of its nuclear sites in the near future.
"Certainly we have committed ourselves to sign the Additional Protocol and that's what we are going to do."
The resolution, adopted by consensus by the 35-nation board of governors of the IAEA, followed days of intensive negotiations between the US and the Europeans - France, Germany and Britain - over how to respond to Tehran.
The IAEA had admonished Iran for concealing aspects of its nuclear programme for nearly two decades and a recent report from the agency said Tehran had been secretly enriching uranium and producing plutonium.
Should any further serious Iranian failures come to light, the board of governors would consider... all options at its disposal
The United States accuses Iran of trying secretly to develop nuclear weapons - an accusation Tehran denies.
Washington originally rejected a draft resolution put forward by Europe as too weak - insisting it should contain a threat of action by the UN Security Council.
However, Britain, Germany and France were concerned that this might alienate Iran, which has shown increased co-operation with the IAEA in recent weeks.
The BBC's Jon Leyne in Washington said that, despite America's concession, the resolution is still harder on the Iranians than France, Britain and Germany had wanted.
The European countries originally called on Iran to continue its commitment to open its nuclear facilities to strict IAEA scrutiny.
French President Jacques Chirac said the compromise deal was "in line with efforts made by the international community to convince the Iranians to genuinely take lasting steps that will rebuild confidence".
The Iranians say their nuclear programme is designed to meet the country's energy needs only.
Although the IAEA says Tehran has breached nuclear safeguards for almost two decades, it also said there was no evidence of an Iranian nuclear weapons programme.