Iran insists its nuclear programme is for peaceful uses only
US President George W Bush has said that the world will not accept the development of nuclear weapons by Iran.
"The international community must come together to make it very clear to Iran that we will not tolerate the construction of a nuclear weapons. Iran would be dangerous if it had a nuclear weapon," he said.
Earlier, at a meeting of the United Nations nuclear watchdog, the United States accused Iran of repeated "violations and evasions" of international
Iran denies any wrongdoing, and says its programme only concerns nuclear energy - not weapons.
Mr Bush also voiced support for opponents of Iran's Islamic regime who have been holding protests to demand reform.
"They need to know America stands squarely by their side and I would urge the Iran Government to treat them with the utmost respect," he said.
At a meeting of the International Atomic Energy Authority (IAEA), US ambassador Kenneth Brill said Iran had not co-operated with nuclear inspections.
He urged Tehran unconditionally to accept tighter international restrictions on its nuclear facilities.
He accused the country of engaging in "a long-term pattern of safeguards violations and evasions regarding a number of its nuclear...activities".
The IAEA's Director General, Mohamed ElBaradei, has issued a report accusing Iran of failing to declare some aspects of its nuclear programme.
Iran - a signatory to the nuclear Non-Proliferation Treaty (NPT) which aims to prevent the spread of nuclear weapons - has rejected allegations by the IAEA that it has failed to disclose information on its use of nuclear material.
Its ambassador to the IAEA, Ali Salehi, told the meeting that nuclear weapons had "no place" in the country's defensive doctrine.
"Iran considers the acquiring, development and use of nuclear weapons inhuman, immoral, illegal and against its very principles," he said.
Mr Salehi added that the IAEA report had not been compiled in an accurate and impartial manner, and implied that other countries, specifically the US, had influenced its writing.
"[The report reflected] the awkward directives
issued from certain influential capitals on the form, the content and the final conclusion and judgement of the report," he said.
The IAEA has called on Iran to sign an additional protocol to the nuclear NPT allowing more intrusive, short-notice inspections of its facilities.
Mr Salehi said earlier that his country was still considering the issue.