Police released a sketch of the suspect, who authorities said came up behind the girl as she was walking to Arlington High School at about 7:45 a.m. on Jackson Street near Saguaro Road.
The suspect told the victim to go with him or he would harm her, but when the girl backed away, he ran off.
Police believe the suspect is a black man, about 5 feet, 6 inches to 5 feet, 8 inches tall with a skinny build. He has a tattoo under his right eye, possibly a tear drop, as well as more tattooing on his right cheek.
The man was wearing a blue camouflage-style jacket, dark jeans and a dark beanie.
Anyone with information was urged to call Riverside police.