The girls told police they were walking south on Scotts Valley Drive when a man pulled over in a white sport utility vehicle and asked them for directions, according to Scotts Valley police.
When the girls walked up to the passenger side of the car, the suspect exposed himself, police said.
He is described as a white man in his early 20s with short brown hair and possibly a moustache or goatee. He was wearing a black T-shirt and black pants.
The vehicle is a small SUV with an uncovered tire mounted on the rear.
Anyone with information about the case is asked to call Scotts Valley police at (831) 440-5670.