The incident occurred around 2 a.m. while the victim was walking in the area of Dutton Avenue and Funston Drive, the sheriff's department said.
The suspect attempted to convince the teenager to get into his vehicle by offering her a ride but when she declined, officials said he got out and assaulted her, causing minor injury.
County officials describe the suspect as a Hispanic man, standing 5 feet 6 inches, with a thin build. He was clean-shaven and had short, dark hair. He spoke with a Spanish accent and was driving a newer model, gray, four-door sedan.
Anyone with information about the suspect is urged to call Detective Joel Pedersen at (707) 565-7600.