The teenager suffered injuries to his face in the incident at around 5pm on Friday on Pittodrie Lane.
He was treated at Aberdeen Royal Infirmary before being released.
He was wearing dark clothes with a hood up and was riding a black bike.
Police Constable Keri Dunn said: "This was despicable behaviour which will not be tolerated.
Anyone with information is asked to contact police on 101, quoting incident number 2947 of November 8.