Arquette, 39, was "OK" after the crash, and was on his way to being treated, publicist Cindy Guagenti told The Associated Press in an e-mail.
"I got into a car accident but I'm fine. Luckily I have dragon's blood running through my veins," Arquette quipped on his Twitter account about two hours after the accident. "Haha. Thank you for all your concern."
In another Tweet, he said: "Remember to wear your seatbelt - wish I was."
Arquette and the other driver were the only two people involved in the collision that happened on Doheny Drive, just north of Santa Monica Boulevard along the West Hollywood border, Beverly Hills police and fire officials said. There was no immediate word on what caused the crash.
Both were taken to Cedars-Sinai Medical Center in Los Angeles with injuries that were not considered serious.
Celebrity website TMZ, which first reported the accident, posted pictures that showed Arquette lying on a patch of roadside grass next to his silver Cadillac and another vehicle. Both had damage on their front bumpers and air bags deployed.
Video posted on the site showed paramedics and firefighters putting a man that appeared to be Arquette on a stretcher and lifting him into an ambulance.
Arquette and wife Courteney Cox announced that they were separating in October. The pair met when they appeared in the film "Scream" in 1996, and are co-starring in the fourth installment of the horror series due out later this year. They have a 6-year-old daughter together.
Arquette has also starred in the films "Never Been Kissed" and "3000 Miles to Graceland."