The attackers, who had their faces covered, approached the victim as he was sat with friends and asked for him by name before repeatedly punching and kicking him to the face.
West Yorkshire Police said the incident at Honley Skate Park, in Jaggar Lane, happened at around 9.20pm on Friday.
The victim was taken to hospital for treatment to facial injuries, including a fractured nose.
Acting Sgt Austen Brook, of Kirklees District Rural Patrol, said: “This was a very nasty attack on the victim by a large group of males and the injuries he received could easily have been more serious.
“We would like to speak to anyone who witnessed the incident or who has any information about who was involved or the circumstances surrounding it.”
Anyone with information is asked to contact 101 or call the independent charity Crimestoppers anonymously on 0800 555 111.