Iran has said it will reject any proposal for a complete halt to its uranium enrichment activities.
Iran says its nuclear programmes are peaceful
National security official Hossein Mousavian said Tehran would not be deprived of its legitimate right to a nuclear fuel cycle.
Britain, France and Germany are due next week to present an incentives package aimed at convincing Tehran to give up its nuclear ambitions.
Iran says its nuclear programmes are peaceful and only to generate power.
Correspondents say the US still favours UN sanctions against Iran, but that it is prepared to give the Europeans a final opportunity to negotiate a settlement before next month's deadline for compliance set by the International Atomic Energy Agency.
Window of opportunity
Efforts to get Iran to abandon its enrichment activities have been a failure so far, yet prospects of imposing effective sanctions on Iran through the UN Security Council are uncertain to say the least, says BBC News Online's world affairs correspondent Paul Reynolds.
Mr Mousavian's words appeared to confirm the lack of optimism that an offer to Iran would work.
"We would be willing to consider any package that recognises the full right of Iran to enjoy peaceful nuclear technology within the framework of the [Nuclear Non-Proliferation Treaty]," he told AFP news agency.
"But Iran is not prepared for cessation. Any package including a cessation of fuel cycle work would be rejected by Iran."
However, Mr Mousavian said Iran was ready to consider continuing its suspension of uranium enrichment and discuss new initiatives to provide guarantees that the process would never be diverted to military purposes.
Our correspondent says Britain, France and Germany feel there is a window of opportunity ahead of a meeting of the UN nuclear agency, the International Atomic Energy Agency, on 25 November.
The European offer is said to include a pledge to resume EU-Iran trade talks.
It is also thought to include guarantees that Iran will have access to nuclear
fuel from Russia.