Police received reports on the incident which took place around 3pm on Thursday, March 4 in the Bankhead Playing Field area.
The 11-year-old was assaulted by a group of teenage males, and police believe that there were a number of people who witnesses the crime.
PC Thomas Wright from Bucksburn CPT said "We would like to speak to anyone who was in the area and witnessed this assault.
"It is believed there were numerous people in the playing field at the time of the incident and we urge them to come forward if they have any information that can assist our enquiries."
Anyone with any information can contact Police Scotland on 101, quoting CF0047740321 or incident 2251 of Thursday 4 March 2021, or make a call anonymously to Crimestoppers on 0800 555 111.