A US-military spokesman said he had no knowledge of the non-combatant deaths.
The air assault on Wednesday that caused the deaths were called in to respond to an attack on troops operating in Laghman province, which adjoins the Sarobi area where 10 French soldiers died earlier in the week, the US-led forces said.
"During the operation, more than 30 militants were killed and a large cache of mortar rounds and IED [improvised explosive device] materials were destroyed by the commandos," they said in a statement.
The attacks were called when the area was clear of women and children after about 200 civilians were seen fleeing, and there were no civilian casualties, the statement said.
But an Afghan politician told Al Jazeera that there were at least 20 civilians among the 30 people killed in the air raids.
Later, the Reuters news agency also two unnamed provincial officials as saying at least a dozen civilians had been killed in the attack.
Civilian casualties
About 20 people were wounded in the attack, including an elderly man, four children and eight women, Asadullah Rauf, a surgeon, was quoted by the AFP news agency as saying.
The others wounded were adult males, he said.
The issue of civilian casualties caused by foreign forces hunting Taliban fighters has led to a rift between Afghanistan and its Western backers.
Hamid Karzai, the Afghan president, said this month that air attacks by foreign forces had only succeeded in killing civilians and not in winning the war.
The International Security Assistance Forces (Isaf) said the operation in Laghman was based on "information gathered following a recent attack by militants on International Security Assistance Forces in that area," it said in a statement.
However, it was not related to the Sarobi battle, a spokesman said, in which about 100 Taliban attacked an almost equal number of French Isaf troops in the Uzbin Valley.
Three Polish soldiers serving with Nato were killed on Wednesday, in a roadside blast, the US-led forces said.
Also in Afghanistan on Thursday, Gordon Brown, the British prime minister, visited the main British military base in the southern province of Helmand and met Karzai in Kabul.