Abdul Ghafar Watandar said the air strike took place during an intense battle between Taliban militants and local police on Monday and Tuesday near the village of Ganj Abad in Bala Baluk district, a Taliban-controlled area near the border with Iran.
Watandar said some 30 militants and three police officers died in the battle, while four police officers and several government soldiers were wounded.
Doctors at a local hospital said they had received 19 people injured in the bombing.
Jessica Barry, spokeswoman for the International Committee of the Red Cross, said on Wednesday that their team had traveled to the villages of Geraani and Ganj Abad in the Farah province and saw "dozens of bodies in each of the two locations."
"We do confirm women and children," the Associated Press quoted her as saying.
Afghanistan's government has been increasingly critical of U.S.-led strikes that have led to major civilian losses. According to the United Nations, 552 civilians were killed by NATO airstrikes in Afghanistan in 2008.
Afghan President Hamid Karzai, who is currently on a visit to the United States, ordered on Wednesday an investigation into the killings, and said that he would raise the issue of civilian deaths during a meeting with U.S. President Barack Obama later today.
Afghanistan's Defense Ministry has demanded that NATO-led international troops in the country coordinate their operations, including airstrikes, with local security forces.
"NATO forces must strictly comply with the provisions of an earlier agreement with Afghanistan's Defense Ministry on the coordination of their actions during combat operations," the ministry said in a statement on Wednesday.
