Manchester United  manager Sir Alex Ferguson  has hit out at the Manchester City  fans who disrupted the end of the Red Devils' 3-2 derby victory at the Etihad, which involved a missile striking defender Rio Ferdinand  in the face.After Yaya Toure and Pablo Zabaleta cancelled out Wayne Rooney's first-half double, Robin van Persie struck a winning free kick in injury time provoking an angry response from the home fans, resulting in an object hitting Ferdinand above the eye and drawing blood.A City fan also managed to force his way through the stewards to get on the pitch and remonstrate with referee Martin Atkinson before being restrained by City goalkeeper Joe Hart."It is just unfortunate at the end that a City fan ran on the pitch and that they threw coins at our players. You really don't need things like that," Ferguson told Sky Sports."The same thing happened at Chelsea, which was a bit masked by everything else that happened that day. It was a fantastic game of football between two fantastic teams and we could have done without that."Replays show the defender being struck by a coin-like object while celebrating, before clutching the shirt to his wound and being escorted off the pitch by a match official.Ferdinand has since taken to Twitter to comment on the game and incident, writing: "what a result,3points! Sweet! Whoever threw that coin,what a shot! Can't believe it was a copper 2p....could have at least been a £1 coin."A Manchester City spokesperson has since apologised to the United defender: "We apologise to Rio. We condemn the actions of the individual concerned."We are reviewing the CCTV with the police and our normal security. We will support the police with any investigation and hopefully identify the person as soon as possible."Greater Manchester Police said no arrests have been made in relation to the attack on Ferdinand, but in an unrelated incident, a man was arrested on suspicion of committing a racially aggravated public order offence during the game after racist chanting was heard by officers.