The EU foreign policy head will visit Iran in the next 48 hours in the latest diplomatic effort to persuade Iran to halt nuclear research, Tehran says.
Iran has said it will not suspend uranium enrichment
Javier Solana will present proposals agreed by six world powers in Vienna on Thursday, Iran's foreign minister said.
Manouchehr Mottaki said a breakthrough was possible but added Iran would not halt uranium enrichment - a condition set by the powers for talks to start.
He said Iran would look at the plans before giving a formal response.
The proposals - drawn up by the five permanent members of the UN Security Council and Germany - have not been made public but sources say they could include giving Iran a nuclear reactor and an assured supply of enriched uranium.
Mr Mottaki said Iran had given the go-ahead for Javier Solana to travel to Tehran in the next two days.
Mr Solana's spokeswoman said he was prepared to travel to Tehran on a presentational rather than negotiating trip, though she believed no date had been fixed.
Mr Mottaki said: "We think that if there is goodwill, a breakthrough to get out of a situation [the European Union and US] have created for themselves... is possible."
However, he added: "Negotiations must be without preconditions. No condition for negotiations is acceptable, especially the condition that has been set."
The six powers say Iran should suspends its uranium enrichment programme before negotiations can begin.
Washington believes Iran is trying to make nuclear weapons while Tehran says its programme is for peaceful energy purposes.
The US on Friday warned Iran it would have little time to respond to the package and officials said a rejection could bring UN-imposed penalties.
But Iranian President Mahmoud Ahmadinejad said Tehran would not abandon its right to nuclear technology under Western pressure.