Tehran's ambassador to the IAEA, Ali Akbar Salehi, said he hoped not to reach such a stage "because then things could very easily get out of control".
He added: "And then it could lead to unpredictable consequences. We don't even want to think about such a situation."
On 20 November, the International Atomic Energy Agency's (IAEA) Board of Governors will meet to discuss its report on Iran's nuclear programme.
The IAEA' concluded there was "no evidence" that Iran's nuclear programme was for anything but peaceful purposes, but said the jury was still out.
The United States wants the board to declare Iran in violation of the nuclear Nonproliferation Treaty (NPT), which could lead to UN Security Council sanctions.
"I hope we do not reach such a stage because then things could very easily get out of control... And then it could lead to unpredictable consequences. We don't even want to think about such a situation"
Ali Akbar Salehi,
Iran IAEA ambassador
US National Security Adviser Condoleezza Rice said the report made clear the Iranians had not been truthful in the past about their nuclear activities.
She said it would be wrong to suggest it allayed fears about Iran's nuclear programme.
"And I think the issue now is are they going to be truthful in the future? Are they going to come clean about what had been going on Iran, what is going on in Iran?" she said.
Rice added the international community should keep up the pressure given Iran's track record of secrecy.
The IAEA report said Iran hid a centrifuge uranium enrichment programme for 18 years and produced small amounts of plutonium, useable in a bomb and with scant civilian uses.
Although diplomats said Washington had few allies on the IAEA board, they said it was searching for a compromise with France, Britain and Germany.
These three countries would prefer to encourage Iran to keep cooperating with the United Nations rather than punish past failures.
Such a compromise might include a word synonymous with "violation" in the text of a resolution, couched in compliments of Iran's new style of full cooperation with the United Nations.
But Salehi said this would be "unacceptable" to Iran.
"I think the issue now is are they going to be truthful in the future? Are they going to come clean about what had been going on Iran, what is going on in Iran"
US national security adviser
Referring to a deal struck by the foreign ministers of France, Germany and Britain in October, Salehi said the three countries should keep their word and not support any US-backed IAEA board resolution.
"We are testing how far we can trust the words of the Europeans on this particular issue. We have taken action on our words. We hope that the Europeans also take action on their words," he said.
Iran had agreed with the Europeans to suspend its controversial uranium enrichment programme and sign the NPT Additional Protocol permitting intrusive, short-notice inspections of all its nuclear sites.
In exchange, the Europeans agreed to consider a future exchange of technology. Diplomats have also said there was a tacit agreement not to back a non-compliance resolution.
On Monday, Tehran suspended enrichment and sent an official letter of intent to sign the protocol, as it had promised.