Sean Stewart, 27, had denied the allegations and said he was a victim of mistaken identity.
"We always felt that over time, the truth would always emerge and the victims over time became less sure of the facts," Cole said.
"He's endured a year of terrible publicity ... so he's now very relieved that someone finally got the message," he added.
A call to the Los Angeles County prosecutor, Bradley Lieberman, seeking comment wasn't immediately returned.
Stewart was accused of attacking Tobalus and Ericka Stein after an April 2007 party in the Hollywood Hills above the Sunset Strip.
According to Cole, the couple's large pickup truck and Stewart, in a Rolls-Royce Phantom, were unable to pass each other on a narrow road.
"Words were exchanged" and bystanders in the street began pelting the truck because they felt the driver was being aggressive, Cole said.
At a preliminary hearing, the driver of the Rolls-Royce testified that others outside the car threw things at the pickup and Stewart only left the car when the windshield was shattered.
"Over the course of time, it became apparent to the district attorney's office that it may have been mistaken identity," Cole said of the assault accusations. "There were a lot of people on the street at the time and he was a recognizable face."
The Steins still have a pending assault and battery lawsuit against Stewart but Cole said he was hopeful that it would be resolved.
Cole said he also hopes to resolve another lawsuit by a man who claims Stewart broke his nose in a Hollywood nightclub attack in 2006. That lawsuit also names Stewart's father and a third man.
