Top U.S. diplomats have been scrambling to salvage plans for peace talks with the Taliban after strong objections by the Afghan government.
State Department spokeswoman Jen Psaki said Secretary of State John Kerry has spoken twice with Afghan President Hamid Karzai to ease his concerns. Preliminary negotiations between the U.S. and the Taliban had been expected to start on Thursday in Doha, Qatar, but now the start date is unclear.
Mr. Karzai, apparently irked by the opening of a Taliban political office this week in Doha, canceled talks with Washington on a troop pact governing U.S. presence in the country after NATO forces withdraw in 2014.
Mr. Karzai's objections focused in part on the way the Taliban unveiled the office Tuesday in Doha, with a sign identifying the facility as the "Office of the Islamic Emirate of Afghanistan."
Afghanistan's U.N. representative, Zahir Tanin, says his country "does not recognize such a thing as the Emirate of the Taliban."
In a Thursday statement, he also called the Taliban's initial decision to raise its flag at the Doha office a "reminder of a dark and bloody past from which our country is still struggling to emerge."
The sign at the Qatar office has since been replaced with one identifying the office as the previously agreed upon "Political Office of the Afghan Taliban."
The flag was still flying at the site on Thursday, but on a shorter flag poll.
It appeared the Afghan government's position had not changed Thursday afternoon.
A spokesman for Mr. Karzai said the government still had no plans to send a peace council to Qatar for talks or hold talks with the United States.
Earlier, Kabul said the U.S. decision to meet the militants in a formal setting outside of Afghanistan undermines the role of the Afghan government.
NATO Secretary General Anders Fogh Rasmussen says he hopes talks would start "sooner rather than later."
At a Thursday news conference, he added that reconciliation was never an easy process anywhere in the world.
In neighboring Pakistan on Thursday, Foreign Ministry spokesman Aizaz Ahmed Chaudhry said his country has been holding talks with Afghanistan and the U.S. and supports the Afghan reconciliation process.