The unmanned spy planes fired several missiles at a vehicle in Barmal area of South Waziristan Agency, official sources were quoted as saying by Geo News channel.
Four suspected militants were killed and five more were injured in the attack.
This is the second missile strike since US special forces gunned down the al-Qaeda chief during a raid on a compound in the garrison city of Abbottabad on May 2.
Barmal is part of the Angoor Adda region of South Waziristan Agency that has been repeatedly targeted by US drones.
Local residents said drones were seen hovering over the area after today`s attack.