Greater Manchester Police say the boy was held on suspicion of a racially aggravated public order offense before being released on bail pending more inquiries.
Ferdinand was bleeding from a cut above his left eye after being struck by an object thrown from the crowd while he celebrated United's late winner in a 3-2 victory
City fan Matthew Stott, 21, had to be restrained by goalkeeper Joe Hart as he tried to confront Ferdinand, and was arrested.
Police made nine arrests in all as tempers among rival fans boiled over and officers have appealed for anyone with information about hooligans throwing coins to get in touch.
Nine men will appear in court in January.
The Associated Press was used in this report.