Iranian President Mahmoud Ahmadinejad has described Saturday's nuclear talks with world powers in Geneva as a step forward.
At the meeting, Iran was given a two-week deadline to decided whether it will accept an incentives package in exchange for suspending its nuclear program.
The European Union's foreign policy chief Javier Solana Saturday said he hopes Iran will provide an answer soon.
Iran's top nuclear negotiator, Saeed Jalili, said many of the problems related to the Iranian nuclear dispute can be resolved.
Saturday's closed-door talks were attended for the first time by a senior U.S. envoy - Under Secretary 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.
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.
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 and Reuters.
