Tribesmen said the two missiles were fired on a vehicle in Shinwarsak area near Wana, the headquarters of South Waziristan.
There were conflicting reports about the identity of the slain men.
While some sources said that all victims were local militants, a section of the media reported that all those killed were foreign militants.
Hours before the US drone strike, a suicide bomber killed at least six people in Wana and wounded a top Taliban leader, Mulla Nazir.
Drone attacks have been a matter of major contention between the US and Pakistan with the latter repeatedly terming them a violation of its sovereignty.
