The clash erupted when gunmen fired on what the US military called an offensive patrol in the central province of Uruzgan on Friday.
"An estimated six enemy fighters were killed; the remainder fled the area," the US military said in a statement issued late on Friday.
Taliban insurgents, fighting US and Afghan troops since US-led forces ousted the Taliban government in late 2001, launch frequent raids in the province.
The American military, which said no Afghan or US troops had been hurt in the clash, said its offensive patrols were aimed at rooting out insurgents and disrupting supplies.
"Such patrols are being conducted through the winter months to deny the enemy sanctuary and hinder the enemy's supply efforts," it said.
Mullah Khaksar killed
In other news, Aljazeera reported on Saturday that unidentified armed men shot dead Mullah Mohammad Khaksar, a former Taliban chief of intelligence who was also a deputy interior minister in the Taliban government in Afghanistan.
The Taliban and their conservative Muslim allies are mostly active in the south and east, close to the border with Pakistan.
About 20,000 US-led troops are battling the insurgents and hunting their leaders. Nato has about 10,000 peacekeepers concentrated in Kabul, the north and west.
More than 50 American soldiers were killed in clashes and bomb attacks last year, the bloodiest period for US forces since the Taliban was ousted.