The troops came under attack in Kunar, on Afghanistan's northeastern border, where warlord Gulbuddin Hekmatyar maintains his own militia, the BBC reported.
"The coalition responded to the attack with small arms, machine gun fire and grenades," a coalition statement said.
No coalition troops were injured in the exchange.
Meanwhile, six Canadian soldiers were recovering Thursday from injuries they received in a mortar attack in Kandahar in southern Afghanistan Tuesday night. During the firefight after their patrol was attacked, eight suspected insurgents were arrested, the report said.