Amir Mohammed Akhunzada, the provincial deputy governor, said the air strike happened around 10am in Kajaki district of Helmand province where Taliban fighters, including commanders, were meeting.
In recent weeks, southern Afghanistan has been hit by some of the deadliest fighting since the ousting of the Taliban government in late 2001.
Militants have stepped up attacks in their former heartland, drawing a fierce response from coalition and Afghan forces.
Before Monday's air strike, as many as 372 people, mostly militants, have been reported killed in violence since May 17, according to coalition and Afghan figures.
Canadian soldiers ambushed
Early on Monday, five Canadian soldiers were wounded and up to six Taliban fighters killed during a gunbattle in southern Afghanistan, a coalition military spokesman said.
The Canadian soldiers were on a patrol about 20km (13 miles) west of Kandahar when they were ambushed by militants, said Major Mario Couture, a coalition spokesman.
Five soldiers were wounded, including one who was seriously wounded and flown to Germany for medical treatment, he said.
The body of one militant was left behind, and up to five others were believed to have been killed and their bodies taken away, he said.
The Canadian soldiers were part of an operation in volatile Panjwayi district to root out Taliban militants, Couture said.
On Sunday, the authorities found the decapitated bodies of three police dumped in a field elsewhere in Helmand, two days after they disappeared. Officials blamed Taliban militants for the killings.