Iran has rejected a resolution from the UN nuclear watchdog demanding it should freeze uranium enrichment, calling the demands "illegal".
Tehran threatened to end spot checks of atomic facilities on Sunday if its case was sent to the UN Security Council.
The UN International Atomic Energy Agency (IAEA) on Saturday unanimously adopted a resolution calling on Iran to suspend all uranium enrichment related activities.
"We are committed to the suspension of actual enrichment but we have no decision to expand the suspension," chief nuclear negotiator Hassan Rowhani said.
"This demand is illegal and does not put any obligation on Iran. The IAEA board of governors has no right to make such a suspension obligatory for any country," he added.
He said Iran would stop allowing UN inspectors to make short-notice visits to its atomic facilities if the Islamic Republic's dossier was sent to the UN Security Council for possible sanctions.
"There is no justification to refer Iran's nuclear dossier to the Security Council," Rowhani said.
"If one day they refer Iran's nuclear dossier to the UN Security Council, that day ... Iran will stop implementing the additional protocol and will limit its cooperation with the IAEA."
The additional protocol to the Nuclear Non-Proliferation Treaty allows snap nuclear checks. Iran is implementing its terms although parliament has not ratified it.
US officials are insisting the 35-member board must refer Iran to the UN Security Council when it meets again on 25 November if Tehran does not comply.
Iran rejects US accusations it wants nuclear weapons, saying its activities are only in pursuit of energy.