Iran has imposed an indefinite freeze on international inspections by the United Nations nuclear watchdog.
Iranians say they will not accept being talked to in "insulting tones"
The move was in retaliation to an International Atomic Energy Agency resolution "deploring" Iran's failure to report some nuclear activities.
Hassan Rowhani, of Iran's Supreme National Security Council, said the resolution was "unfair and deceitful".
The US condemned Iran's move, saying it might be an attempt to gain time or hide covert activities.
The chief US delegate to the IAEA, Kenneth Brill, said: "This is a measure of their full co-operation - they're
postponing the very thing that they are called on to do by their obligations."
Iranian foreign ministry spokesman Hamid Reza Asefi on Sunday said there was no timetable for a resumption of inspections.
"This was a response to the insulting tone of the resolution. We don't allow them to talk to us in such a way," he said.
Mohammed ElBaradei is confident Iran will reverse its suspension
"When and how a new date is set, I do not know."
However, Mr Asefi said Iran was still willing to co-operate with the UN agency, because "we are transparent in our intentions and goals".
On Saturday, the IAEA at its meeting in Vienna censured Iran for omitting key atomic technology from an October declaration, although it tempered the criticism with praise for Tehran's increased nuclear openness.
The compromise resolution came after a week of intense negotiations.
Some nations wanted to soften the tone while others, including the United States, were pushing for stronger language.
Mr Rowhani condemned the resolution for not reflecting the reality of Iran's co-operation with the agency.
IAEA chief Mohamed ElBaradei tried to play down the dispute, saying he was confident Iran would reverse the suspension of inspections "in the next couple of days".
The IAEA has a June deadline to present a judgment on Iran's nuclear activities.
Iran insists its nuclear activities are for peaceful purposes such as the generation
The United States suspects it has a secret weapons-making programme and wants the IAEA to declare Iran in breach of the Nuclear Non-proliferation Treaty.