Costa Mesa said it appears the man, believed to be in his late teens or early 20s, followed the woman around in the mall and then out to the parking lot on Aug. 2.
He then approached her as she sat in her car with the door open around 5:38 p.m.
"An unknown male walked up to her and reached up under her skirt and attempted to grab her," said Lt. Paul Beckman with the Costa Mesa Police Department.
After a short struggle, the man ran off.
Police say it has been several years since a crime of this nature occurred at the high-end mall. They note that the facility has security guards as well as police officers always assigned there. Customers who shop there are shocked at the crime, saying they normally consider South Coast Plaza to be a safe place to shop.
The suspect was described as a male, 17-22 years old, 5 feet 8-inches tall with a slim build and dark hair. He was wearing blue shorts, blue shirt and a blue hat with a white logo and gray shoes.
They asked anyone with information to call police at (714)754-5120.