The girl was approached by the driver of a pickup truck in the parking lot of Maria Carrillo High School around 12:10 p.m., police said.
The student said she did not know the driver and when he attempted to convince her to get into his vehicle, she walked away and reported the incident to school officials, according to police.
The vehicle drove out of the parking lot and headed west on Montecito Boulevard, police said.
The vehicle is described as a white extended cab pickup truck with a utility bed and a black lumber rack.
The suspect is described as a Hispanic man between 25 and 35 years old who has black hair, a thin build and was wearing a backward baseball cap.
Anyone with information about the identity of the suspect or location of the vehicle is asked to contact Santa Rosa police at (707) 528-5222.