The European Union's top diplomat says Iran has given no clear answers to an incentives package offered to Tehran in exchange for suspending its nuclear program.
EU foreign policy chief Javier Solana says he hopes Iran will provide that answer soon.
He spoke at a news conference Saturday in Geneva with Iran's top nuclear negotiator, Saeed Jalili, who said many of the problems related to the Iranian nuclear dispute can be resolved.
The two made their remarks after holding closed-door talks that, for the first time, were attended by a senior U.S. envoy, Undersecretary of State William Burns.
Jalili said a letter had been delivered to the U.S. delegation citing "common grounds and discrepancies."
In Washington, the State Department said Iranian leaders must make a choice between cooperation and confrontation.
In a statement, spokesman Sean McCormack said cooperation would bring benefits to all and confrontation can only lead to further isolation.
Iranian and EU negotiators agreed to meet again in two weeks for another round of nuclear talks.
Iran Saturday ruled out suspending its uranium enrichment program - a key demand of Western powers.
A member of the Iranian delegation, Keyvan Imani, said the "freeze-freeze" approach - where Iran would temporarily stop enrichment work in exchange for no new U.N. sanctions - was not on the agenda of today's talks.
Until now, the Bush administration has insisted on shunning nuclear talks with Iran until it stops enriching uranium.
The United States and its Western allies have accused Iran of working to produce a nuclear weapon. Iran says its atomic program is peaceful.
Some information for this report was provided by AFP, AP and Reuters.