Iran insists its nuclear programme is for peaceful energy purposes
Iran has said it is not willing to discuss its "nuclear rights" during an upcoming meeting with the five permanent UN Security Council members.
The head of the country's atomic energy body also ruled out a suspension of Iran's nuclear enrichment programme.
But Ali Akbar Salehi said he would set out when and how inspectors could view Iran's second uranium enrichment plant.
The US has demanded "immediate and unfettered access" for International Atomic Energy Agency (IAEA) inspectors.
Iranian representatives will meet in Geneva on Thursday for talks with the five permanent Security Council seat holders - the UK, China, France, Russia and the US - plus Germany; the so-called P+1.
Mr Salehi said there would be no bargaining about Iran's rights to nuclear technology and said Tehran had no plans to abandon its nuclear activities, "even for a second".
"We are not going to discuss anything related to our nuclear rights, but we can discuss about disarmament, we can discuss about non-proliferation and other general issues," he said.
Iran revealed its second nuclear plant, thought to be near Qom, on 21 September.
The IAEA had requested "specific information and access to the facility as soon as possible" after receiving the letter from Tehran admitting to the existence of the plant.
Mr Salehi told the IAEA that no nuclear material had been introduced into the "new pilot fuel enrichment plant", which Tehran said was still under construction.
Tehran also said that enrichment levels would only be high enough to make nuclear fuel, not a bomb.
Mr Salehi revealed that the new facility had been positioned within a mountain, next to a military site, to protect it from attack.
China has called for restraint ahead of the talks. A spokeswoman for the country's foreign ministry, Jiang Yu, said she hoped that there would be a "relaxation of the situation".
"We hope relevant countries can make efforts. We support the maintenance of the international non-proliferation regime and uphold the proper handling of the issue through negotiations," she said.
Her comments came amid tensions between Iran and the West that have escalated yet further in the days leading up the talks in Geneva.
Iran has test-fired a series of medium- and longer-range missiles that put Israel, parts of Europe and US bases in the Gulf within potential striking range.
The White House called the move "provocative" but Iran's foreign ministry said the tests were merely part of an annual military drill, and were not a reaction to the nuclear crisis.
Iran insists that all its nuclear facilities are for peaceful energy purposes and rejects accusations from the US and others that it is seeking a nuclear weapon.
US President Barack Obama has hinted at pursuing tougher sanctions against Tehran if progress over the crisis is not made.
Russia recently signalled it might be prepared to soften its opposition to further sanctions.
China, which is also a permanent Security Council member, has said such pressure would not be effective.