"Now that negotiations are supposed to be held, why are you setting deadlines and giving ultimatums?" Rafsanjani asked in a Friday prayers sermon carried live on state radio.
"Iran is ready to go there and talk — say whatever you have to say there," said the former president who currently heads two of Iranian regime's top clerical and arbitration bodies in Iran.
"Do not try to find fault. Be patient and let wise people sit down and talk to resolve this issue in the negotiations which have started," Rafsanjani added, addressing world powers.
The mullahs' are under a two-week deadline to give a final answer to world powers seeking a breakthrough in the nuclear crisis, after Saturday talks in Geneva with EU foreign policy chief Javier Solana ended in stalemate.
Iranian regime's officials have repeatedly said they have no intention of freezing enrichment.
Ahmadinejad told a rally in the southwestern province of Kohgelouyeh-Boyerahmad on July 23, "The Iranian people are steadfast and will not step back an inch against the oppressive powers."
He welcomed the US presence in talks as a "positive step" but vowed that further sanctions would not force Iran to back down in the nuclear standoff.
"The Iranian nation does not value your threats. You are mistaken if you think you can force this nation to back down with sanctions, threats and pressure," Ahmadinejad said.
The mullahs' president advised US officials "not to ruin your positive step with irrelevant comments and a colonialist language" in the speech broadcast on state television the same day.
The clerical regime, with all of its players, has one strategy which they reverberate at different occasions; buy time.