The UN's nuclear watchdog has passed a resolution expressing "deep and increasing concern" about Iran's nuclear programme.
The IAEA resolution called on Iran to clear up outstanding questions about its nuclear capabilities, but did not refer it to the UN Security Council.
A recent IAEA report said Iran had carried out tests "relevant to the development of a nuclear device".
Iran's IAEA envoy said the resolution would only strengthen Iran's resolve.
"It will be business as usual... We will continue our work as before," Ali Ashgar Soltanieh told reporters.
Iran insists that it is enriching uranium only to use as fuel for nuclear power stations. However, the US and its allies believe it is trying to develop a nuclear weapon.
The resolution was adopted by 32 votes against two - Cuba and Ecuador - at an IAEA meeting in Vienna.
The IAEA has been debating its recent hard-hitting report on Iran - released last week in the Austrian capital.
The resolution asks Iran to clarify matters "to exclude the existence of possible military dimensions" to its nuclear programme.
The document also says it is "essential for Iran and the agency to intensify their dialogue".
BBC diplomatic correspondent Jonathan Marcus says the resolution - drawn up by the US, Britain, China, France, Russia, and also Germany - is essentially a trade-off.
Russia and China have come on board to share in the concern about Iran, but the resolution itself is thus less tough than the US and its allies would have wanted, he says.
US envoy to the IAEA Glyn Davies rejected criticism that the resolution was too weak.
"This resolution... gives us the tools we need to get the job done," he said.
The White House also welcomed the IAEA resolution.
Spokesman Jay Carney said it exposed "the hollowness of Iran's claims" that its nuclear programme was purely for civilian purposes.
The General Assembly also overwhelmingly backed a resolution condemning an alleged assassination plot targeting the Saudi ambassador to the US, which Washington has accused Iran of being behind.
Without directly accusing Tehran of the plot, the resolution called on it to "to comply with all of its obligations under international law" and to "co-operate with states seeking to bring to justice all those who participated in the planning, sponsoring, organisation and attempted execution of the plot."
Iran has strongly denied any involvement in the plot and sought to have all references to it removed from the resolution, which was proposed by Saudi Arabia.
Tehran has threatened to take legal action against the IAEA for issuing its recent report.
Iran alleged that the report's findings were made under political pressure from the US.
The IAEA has proposed sending a high-level mission to Iran to address the fears.