At around noon Wednesday, police say the man approached the young girl at the Bodega Ranch Market on Walnut Avenue.
He allegedly exposed himself and touched her back before fleeing.
Tustin police released surveillance photos of the suspect. He is described as an Asian man, 30 to 40 years old, standing 5 feet 3 inches tall, weighing 150 pounds with black hair and a mustache. He was last seen wearing a black T-shirt, dark colored shorts, white socks and dark colored shoes.
If you have any information about this case, you're urged to contact Detective Nguyen with the Tustin Police Department at (714) 573-3253.