"We have nothing more to add. It is the third party or third country that should cooperate with the IAEA," foreign ministry spokesman Hamid Reza Asefi told reporters.
A report by the head of the International Atomic Energy Agencyreleased on Tuesday said agency inspectors had found more traces in Iran of highly enriched uranium that could be bomb-grade.
But Iran has consistently contended that such traces came into the country on equipment bought on an international black market, in which most of the parts came from Pakistan.
The IAEA is pressing Pakistan to allow its inspectors access to verify Iran's insistence that the traces -- of uranium enriched to a level beyond that needed for civilian purposes -- were not from domestic enrichment activity.
The source is one of the "outstanding" issues the IAEA has with Iran, which denies US allegations it has a covert nuclear weapons programme.
But Asefi also accused IAEA chief Mohamed ElBaradei of "nit picking" in his latest report on Iran, released ahead of a June 14 meeting of the Vienna-based body's executive.
"This report has nothing new to say. It is a repetition of previous issues, but written in a different way," Asefi said, before complaining that the report had generated yet more suspicions.
"Rather than referring to our non-cooperation, the report is just nit-picking," he said, asserting ElBaradei's findings "show there is no evidence for keeping the file open."