The bomber, described as 10 to 15 years old, pushed a hand cart carrying explosives into a vehicle carrying Nazir's aides in the South Waziristan tribal region's Wana area, Pakistan's Dawn News reported.
Geo News described the attacker as riding a motorcycle.
Assistant Political Agent Shahid Ali Khan said six people were killed and nine others injured in the blast. At least four of Nazir's aides were killed in the attack, Dawn News said.
Nazir, who was standing near the car, suffered a slight injury to his leg.
Three vehicles and eight nearby shops were destroyed.
Nazir is an influential Taliban leader whose group is accused of attacking foreign troops in neighboring Afghanistan. U.S. drones have repeatedly targeted the anti-U.S. commander.