A senior nuclear negotiator has confirmed Iran's resumption of small-scale uranium enrichment work, saying it began at Natanz last week.
Vaidi said it would be "unacceptable" to halt research
But Javad Vaidi said Tehran would now send a delegation to Russia for talks on 20 February to discuss a proposal to enrich uranium on Russian soil.
Iran had postponed the talks and vowed to resume enrichment after it was reported to the UN Security Council.
Western nations suspect Iran is attempting to build nuclear weapons.
Iran insists its nuclear programme is solely for peaceful purposes.
Before making a speech at a student conference in Tehran, Mr Vaidi confirmed small-scale enrichment work had been restarted at Natanz.
"In accordance with parliament's ratification, the president ordered work to resume," he said.
The Iranian parliament, or Majlis, passed a law obliging the government to take this step if it was reported to the Security Council by the International Atomic Energy Agency (IAEA).
However, Mr Vaidi denied Iran had restarted large-scale enrichment by injecting uranium hexafluoride (UF6) gas into centrifuges, as alleged by diplomats in Vienna on Monday.
"We need time to make 60,000 centrifuges," he said.
'Interaction and understanding'
Despite the IAEA resolution, Mr Vaidi revealed Iran was still prepared to discuss Russia's proposed compromise on uranium enrichment at talks now scheduled for next week.
"We are still ready for negotiations with everyone including the Europeans, the Non-Aligned Movement, China, Russia and others. We want to achieve a formula through interaction and understanding," he said.
"We call on the West not to create any problems for us, because we do not intend to cause any for them."
The IAEA's board is expected to meet at the beginning of March to consider whether to recommend action on Iran by the Security Council.
Mr Vaidi said it would be "unacceptable" for Iran to halt research on the enrichment process, whatever the IAEA decided.
"Iran will not compromise its independence and national security," he said.