WASHINGTON, Nov. 13 (Xinhua) -- The United States said on Monday that it has stopped its effort to seek direct contacts with Iran on ways to ease unrest in Iraq, saying that channel of communications "didn't work out."

    "We went through a period where there was an offer of that channel of communications," said State Department spokesman Sean McCormack, referring to contacts between the U.S. ambassador in Baghdad and Iranian authorities.

    "It didn't work out for a variety of different reasons," McCormack said of the contacts between Ambassador Zalmay Khalilzad and the Iranians, which had been authorized by U.S. Secretary of State Condoleezza Rice.

    "If in the future we want to avail ourselves of that channel, then that is certainly a possibility, but I don't think that right now that is something that is under consideration," McCormack said.

    The spokesman made the remarks shortly after U.S. President George W. Bush told reporters at the White House that Washington will not have direct talks with Tehran unless it suspends its nuclear program.

    "If the Iranians want to have a dialogue with us, we have shown them the way forward, that is, for them to verifiably suspend their enrichment activities," Bush told reporters after meeting with Israeli Prime Minister Ehud Olmert.

    U.S. Ambassador to Iraq Zalmay Khalilzad was authorized in May to discuss Iraq with officials in Iran, which Washington has accused backing anti-U.S. insurgents in Iraq.

    Iran at first agreed to accept the U.S. offer, but soon changed its mind, saying the Americans had raised "other issues," apparently referring to the suspension of uranium enrichment.

    The U.S. has been demanding Iran stop uranium enrichment which is a necessary step both in nuclear energy making and the making of a nuclear bomb.

    Iran insists its nuclear program is solely for civilian energy purposes.

    Washington and Tehran have severed diplomatic relations since Iranian students stormed in 1979 the U.S. Embassy in Tehran and held its occupants hostage for 444 days to protest Washington's refusal to hand over the toppled shah, Mohammad Reza Pahlavi.