A military statement said on Sunday the strikes were launched after a patrol reported being pinned down by small-arms and rocket-propelled grenade fire northwest of Giriskh district in the southern province of Helmand.
"US aircraft and attack helicopters engaged the enemy," the statement said. "Initial battle-damage assessments indicate 15 to 20 enemies died and an enemy vehicle was destroyed."
Military spokesman Colonel Jim Yonts said the patrol was made up of both US and Afghan troops. The statement said the US-led force suffered no casualties.
"When these criminals engage coalition forces, they do so at considerable risk," the statement quoted another spokesman for the US military, Lieutenant Colonel Jerry O'Hara, as saying.
Meanwhile, Taliban guerrillas said they executed a district police chief and seven other policemen on Sunday out of 31 police they were holding prisoner in the southern Afghan province of Kandahar.
The capture and killing of the men has created a fresh crisis for authorities in Kandahar, the province worst hit by a growing insurgency in recent months that has raised fears for parliamentary elections on 18 September.
In separate developments in neighbouring Helmand province, fighters killed a judge, an intelligence official and a guard in the district of Anad-i-Ali to the west of the provincial capital Lashkargah on Friday night, a provincial spokesman said.
Overnight, three rockets hit the city of Kandahar, one of which seriously wounded two children, police said.
A senior police officer said on Saturday that the Taliban had captured 30 policemen and a police chief in attacks on Thursday and Friday on Mian Nishin, a district in the north of Kandahar province, and taken over the main government
Taliban spokesman Abdul Latif Hakimi said district police chief Nanai Khan, the senior policeman captured, was shot dead with three bullets on the orders of Taliban religious leaders.
"At 8.30 this morning we executed Nanai Khan after a fatwa from the mullahs"
Abdul Latif Hakimi,
"At 8.30 this morning we executed Nanai Khan after a fatwa from the mullahs," he said. "They said his crime was high so he should be executed."
The officer's body was dumped at a village in Mian Nishin named Shai Khan, Hakimi said. "The government can come and pick up his body," he said.