A report by U.S. nonproliferation experts this week said Iran could produce enough weapon-grade uranium for one or more nuclear bombs by mid-2014, and that Washington and its allies should intensify sanctions.
Analysts and diplomats see a window of opportunity for world powers to make a renewed diplomatic push to find an overall negotiated solution to the dispute after U.S. President Barack Obama won re-election in November.
The six powers want Iran to scale back its uranium enrichment program and cooperate fully with the IAEA. Iran wants the West to first lift sanctions hurting its economy.
Both sides say they want to resume talks soon, but have yet to announce a date and venue.
Iran's Mehmanparast also reiterated that a religious edict from clerical Supreme Leader Ayatollah Ali Khamenei banning nuclear bombs is binding on Tehran and suggested this should defuse concerns about Iranian nuclear ambitions.
"There is nothing more important in defining the framework for our nuclear activities than the leader's fatwa," Mehmanparast said. "This fatwa is our operational instruction."
Khamenei's fatwa, according to a September 2012 report by the Fars news agency, prohibited the production, stockpiling and use of nuclear weapons and said they contradict "Islamic beliefs and the principles of the Islamic Republic of Iran".