Karzai said there were civilian casualties as a result of air raids in the Shah Wali Kot district of Kandahar province.
David Chater, reporting for Al Jazeera from Afghanistan, said he had been told by a cameraman that a coalition patrol had gone through a village and was fired on by Taliban forces at some distance.
"As a result of that Taliban fire they called in closed air support and there was a wedding party going on in that village - there were some 90 people in a house - and the missile landed there," he said.
He said there was no confirmation either from multinational forces, the Americans or indeed from anybody about the number of casualties.
A correspondent reporting for Al Jazeera said around 30 Afghan civilians, including women and children, had been killed in the air raids.
Dozens were still trapped under the debris, the correspondent said.