A man grabbed her arm and tried to drag her to a secluded portion of the park, according to the Sheriff's department.
The girl broke away and ran to her cousin, who was playing nearby, and park personnel called law enforcement.
The suspect is described as a white male in his 30s, about 5 feet, 10 inches tall with a medium build. He was wearing a white T-shirt, brown shorts and dark sunglasses.
He drove away in a silver compact car with a spoiler.
Anyone with information is encouraged to contact the Los Angeles County Sheriff's Parks Bureau at (800) 834-0064. Anonymous tips can be made by calling (800) 222-TIPS (8477).