"Renouncing nuclear technology or enrichment is not something that Iran will accept a compromise on," foreign ministry spokesman Hamid Reza Asefi told reporters.
"We are not developping weapons of mass destruction. Our activities are transparent," he added, in response to weekend statements on Iran by US President George W. Bush and Russian President Vladimir Putin.
The International Atomic Energy Agency (IAEA) has given Iran until October 31 to answer all its questions concerning allegations that it is seeking to develop atomic weapons.
It has also called on the country to cease uranium enrichment, amid the discovery by IAEA inspectors in Iran of traces of highly enriched uranium -- traces that Iran insists were imported along with equipment from overseas.
On Saturday Bush and Putin discussed Iran, with the Russian leader saying that a "clear but respectful signal" should be sent to Tehran about the need to cooperate with the IAEA over its nuclear facilities.
Bush, for his part, called on Tehran to come clean on its nuclear programmes and said "it is in our national interests to make sure that Iran does not develop a nuclear weapon."
The United States is pressing Russia not to sign an accord that would allow Iran's first nuclear power plant -- which is being built by Russia -- to go online.
On Thursday, Iranian President Mohammad Khatami described the IAEA ultimatum as "unjust". If Iran does not meet IAEA demands, the agency could send the issue to the UN Security Council, which could then impose sanctions.
And the IAEA said Friday that the planned departure Sunday of UN nuclear inspectors to Iran has been delayed "until the end of next week" as Tehran wanted more time to prepare for the visit.
The mission of a senior IAEA delegation that was to leave Vienna on Sunday was to have been the first wave of more than a month of intense inspections right up until the October 31 deadline.