Iran's Press TV reported the blast occurred about 7 p.m. local time in the Nahrawan neighborhood of southeast Baghdad.
The network's Iraqi security and hospital sources said most of the victims were teenagers.
Press TV said soccer players and their fans have become a target of choice for terrorists lately, supplanting mosques, markets and security forces. The reason for going after the athletes and their followers wasn't clear, the network said.
Bombings Thursday, Friday and Saturday killed about 50 soccer players and spectators, and injured more.
Overall, more than 2,000 people have died in attacks across the country since April 1.