"When we make an undertaking at the international level, we respect it," the official said, asking not be identified.
"We have handed over a full, clear and detailed report. At the moment our cooperation (with the International Atomic Energy Agency) goes beyond that required by the additional protocol (of the nuclear Non-Proliferation Treaty).
"Once we have actually signed it, we will work within the framework laid down by the protocol."
Ahead of Friday's deadline set by the IAEA last month, Iran had made a string of concessions to fall into line with the watchdog's demands.
Last week, it handed over a massive report on its nuclear programme, which IAEA director general Mohamed ElBaradei said Thursday "at first glance ... looks comprehensive."
During an unprecedented joint visit by the British, French and German foreign ministers earlier this month, it also pledged to suspend uranium enrichment and sign up to the tougher inspections regime set out in the additional protocol.
Iran's archfoe the United States has since expressed some scepticism about the Islamic regime's readiness to deliver on its undertakings.
"(The Iranians) need to follow through on what they've committed to do and meet their international obligations," White House spokesman Scott McClellan said Wednesday.
Iran has yet to actually suspend uranium enrichment or formally notify the IAEA of its intention to sign the additional protocol.
But its representative to the watchdog, Ali Akbar Salehi, said Tuesday that halting of Iran's work on the nuclear fuel cycle was "probably a matter of weeks." The letter for the IAEA had already been drafted and would be delivered in a "matter of days", he said.