Officials said the victim was walking home from school around 3 p.m. Monday near Las Rosas Drive and Evans Street when a man approached her and asked her if she wanted to have sex.
When the victim refused, the suspect touched her and threatened to kill someone in her family if she told anyone.
Police released a composite sketch of the suspect, who was described as a white male in his late teens, with blonde hair, a thin build and a nose ring. He was wearing a baseball cap backwards, a white T-shirt and dark skinny jeans.
Anyone with information about the suspect was asked to call San Jacinto police at (951) 654-2702.