The suspects, believed to be between 10 and 12 years old, approached the driver around 6:45 p.m. in the area of Black Oak Road and Meadowbrook Drive, said San Diego police Officer David Stafford.
At least one suspect displayed a handgun and demanded cash from the victim, Stafford said.
The suspects fled on foot with an unknown amount of cash, Stafford said.
The ice cream truck driver was not injured.
Descriptions of the suspects were not available.