He added police had not received a good response from some of those at the scene.
While the teenager's assailant had not been identified police did uncover a knife and a screwdriver.
The incident did not appear to be gang related.
About a dozen people had been involved in the fighting.
No arrests had been made at edition time.
"We are appealing for any information that may assist with this Inquiry," Eastern DCC Senior Sergeant Sarah Thorn said.
In April an out-of-control party in Marewa resulted in 15 arrests after about 1500 young people turned up in the wake of it being announced on Facebook.
Fights broke out and vehicles were damaged.
Anyone with information on the weekend's stabbing is asked to contact Mr Restieaux on 831 0700.