The suspect was described as a Hispanic man, 20 to 25 years old, 5 feet 10 inches tall and 150 pounds.
According to sheriff's deputies, on Sept. 24, a woman was changing in a dressing room when the suspect reached under the door with a cell phone and tried to take a picture.
The woman grabbed the phone out of the suspect's hand. The man became agitated and started banging on the door.
He eventually crawled under the door and got into the stall with her. There was a scuffle, and she called for help.
"Store personnel came and separated it. The guy was able to get up and run out of the store," said Lt. Steve Sciacca of the Los Angeles County Sheriff's Department.
The woman was not harmed, but the suspect got away with his cell phone.
"People are crazy. They'll do anything. I'm always looking underneath, because you never know," said a shopper.
Anyone with information was urged to call Crime Stoppers at (800) 222-8477.