Top EU diplomat Javier Solana handed Iran an offer by six major powers of trade and other benefits on Saturday to try to coax it into halting sensitive nuclear work, but Tehran again ruled out any such suspension.
The United States and its European allies have warned the Islamic Republic of more sanctions if it presses ahead with a nuclear programme they fear is aimed at making bombs.
The world's fourth-largest crude producer is refusing to stop activities it says are for generating electricity.
"Iran's view is clear: any precondition is unacceptable," government spokesman Gholamhossein Elham said when asked about the package of incentives offered by the United States, China, Russia, France, Britain and Germany.
"If the package includes suspension it is not debatable at all," he told reporters.
Although Iran has not officially rejected the offer, U.S. President George W. Bush said he was disappointed when asked about Elham's statement during a visit to Paris.
"I am disappointed that the Iranian leaders rejected this generous offer out of hand," Bush told a joint news conference with French President Nicolas Sarkozy, adding it was a sign that Iran's leadership was willing to isolate its people further.
Elham was speaking shortly after Solana, the European Union's foreign policy chief, presented the proposal to Iranian Foreign Minister Manouchehr Mottaki.
The offer, including civilian nuclear cooperation, is a revised version of one rejected by Iran two years ago and diplomats have played down any hopes of a breakthrough in a dispute that has helped push up oil prices to record highs.
