NATO only confirmed military deaths so far in the pre-dawn strike Wednesday on a house in Logar province. It sent a team to investigate the claims that civilians were killed.
Wednesday was a particularly deadly day for Afghanistan as a trio of suicide bombers killed 22 people in the busy marketplace of Kandahar city.
Meantime, U.S. Defense Secretary Leon Panetta arrived in Afghanistan Thursday as part of a trip to discuss plans for the troop drawdown and take stock of progress in the country.
Officials said 23,000 American troops will be withdrawn by September, leaving about 68,000 U.S. military personnel in the country.
The Associated Press contributed to this report.