The spokesman said that on Tuesday morning approximately 25 militants attacked a NATO-led ISAF convoy south of the administrative center of Lashkargah. Because of the threat, ISAF called for air support, which dropped a bomb in the area of the militants.
"'The ISAF troops, however, were not aware that the insurgents were once again using civilians as human shields," the spokesman said.
There was no information if any of the militants were killed in the bombing and a joint Afghan-ISAF investigation is ongoing.
Civilian casualties caused by NATO forces have been the main source of tension between the government of President Hamid Karzai and the approximately 70,000 international troops in the country.
The worst incident happened in the western province of Farah earlier this month, where the Afghan government says US airstrikes killed 140 villagers.
The US military said in a statement on Wednesday that a much lower number of civilians lost their lives in the May 4 attack and blamed the Taliban for endangering the lives of villagers during the battle.
