Seleka rebels started an offensive in CAR in December, capturing key cities, including a regional diamond center. The rebel consortium accuses the government of failing to honor a 2007 peace deal that saw their forces paid off in exchange for surrender.
The movement said it halted its planned assault on CAR's capital Bangui. Defense Minister Francis Bozize told the BBC that regional forces were staged about 48 miles outside the capital.
Victoria Nuland, a spokeswoman for the U.S. State Department, said Washington was calling on all parties to take part in negotiations hosted by the Economic Community of Central African States.
"We call on the rebel alliance to cease hostilities and movements toward the capital," she said in a statement. "We also call on the rebels to ensure the safety of the civilian population."
A similar statement of concern was expressed by the European government, which said it had deep and growing concerns about the crisis in CAR. All sides, the European Commission said in a statement, are called on to avoid using military force for political gain.