Britain, France and Germany, signatories to Iran's 2015 nuclear deal, reimposed sanctions on September 28, triggering in turn the return of UN sanctions under the so-called snapback mechanism.

"We have no plans for negotiations at this stage," ministry spokesman Esmaeil Baqaei said, adding that Iran was examining the "consequences and implications" of the restart of sanctions initiated by the countries known as the E3.

"Of course, diplomacy -- in the sense of maintaining contacts and consultations -- will continue," Baqaei said.

"Whenever we feel that diplomacy can be effective, we will certainly make decisions based on the country's interests and priorities," he added.

Western countries, spearheaded by the United States and joined by Israel, accuse Iran of pursuing nuclear weapons and define uranium enrichment as a red line.

Iran categorically rejects the accusations, insisting its nuclear programme is solely for civilian purposes and that it has a right to enrichment under the nuclear Non-Proliferation Treaty.

According to the International Atomic Energy Agency (IAEA), Iran is the only country without a nuclear weapons programme to enrich uranium to 60 percent, close to the threshold of 90 percent required for a bomb.

In 2015, the United States, with the three European countries, Russia, and China concluded an agreement with Iran providing for the regulation of Iranian nuclear activities in exchange for the lifting of sanctions.

President Donald Trump decided during his first term in 2018 to withdraw from the deal and reinstate sanctions.

In retaliation, Iran has gradually withdrawn from some commitments, particularly on uranium enrichment.

Iran has repeatedly warned that a return of sanctions would lead to a suspension of cooperation with the IAEA.

On Sunday, Iran's Foreign Minister Abbas Araghchi warned that cooperation with the IAEA, the UN's nuclear watchdog, "is no longer relevant" with the reintroduction of UN sanctions, though it was not clear whether Iran intends to completely break with the agency.