The 14-year-old victim was initially chased around a funfair on the Stray in Harrogate by the group, who were aged between 14 and 18.
She ended up on the floor, where she was punched and kicked. She was also hit in the head with a bottle and needed hospital treatment.
Police are appealing for witnesses to the incident, which happened between 6pm and 7pm on Sunday.
Contact 101 with information.