Six people, including the two recording artists, were involved in the fight Sunday night at Westlake Studio.
Police were called to the scene to break it up, but no arrests have been made.
When they arrived, investigators spoke to Ocean, but Brown was already gone, TMZ said.
The celebrity news website cited unnamed sources close to Brown as saying Ocean and his entourage started the argument by blocking Brown's car when he was trying to leave.
The witnesses said one of Ocean's friends attacked Brown when he attempted to shake the hand of his fellow singer, then one of Brown's companions hit Ocean's friend in retaliation. Ocean then attacked Brown and a brawl erupted, TMZ said.
Brown pleaded guilty to assaulting and threatening his then-girlfriend Rihanna during a heated argument in a car in 2009. He was placed on five years probation and ordered to complete community service. He and Rihanna recently reconciled.
Last year, he and Canadian singer Drake had an altercation at a New York nightclub, which left eight people injured. No arrests were made.
Senate Democrats to pull all-nighter on climate change
Scarlett Johansson steps out with fiance after pregnancy reveal