Efron, 26, and a man, he identified as his bodyguard were reportedly found by the police on March 24 fighting with several men under the Harbor Freeway, reported TMZ.
The actor is believed to have told the police that they were waiting in their car for a tow as it had run out of petrol.
While waiting, they threw a bottle out of the window and it smashed on the pavement near a group of men who appeared to be homeless.
The actor said the two of the homeless group attacked the bodyguard, and when Efron got out of the car he allegedly got punched in the mouth.
"It was the hardest I've ever been hit in my life," Zac reportedly said after meeting the cops.
No one was reportedly arrested as policed viewed the incident as "mutual combat.