"We will study the offer and, God willing, will give our opinion at the end of the Mordad," Ahmadinejad said in a speech, referring to the Iranian month that ends on August 22.
The proposal from the five permanent UN Security Council members — Britain, China, France, Russia and the United States — plus Germany was presented to Iran on June 6. Diplomats say Iran was asked to reply by June 29.
The offer involves incentives and multilateral talks if Iran agrees to suspend uranium enrichment — at the centre of fears it could acquire nuclear weapons — and cooperate with the International Atomic Energy Agency (IAEA).
But Iran has so far only said it wants fresh negotiations without preconditions — indicating it will not stop enriching uranium.
The country argues it only wants to make civilian reactor fuel, although the process can be extended to make the fissile core of a nuclear weapon — and Ahmadinejad gave yet another signal that Iran would not stop enriching.
"We want to fully exploit our definite and legitimate rights. Today, our nation, with its capable hands, has achieved full nuclear fuel technology," he asserted in the speech in the western city of Hamedan.
"We want peace and calm for all nations. Based on our definite rights, we will negotiate with everyone … but negotiations should be as equals and without any preconditions imposed," Ahmadinejad said in the speech, which was carried live on state television.