The club viewed CCTV footage which identified a 17-year-old youth picking up the ball.
It then decided that the matter should be brought to the attention of Greater Manchester Police who arrested him on suspicion of theft.
Shortly after his arrest he was 'de-arrested' when Manchester City opted not to press charges and instead arranged a meeting with him to ask for their ball back.
A spokesman for Greater Manchester Police said... .'It was decided the most appropriate cause of action was to use Restorative Justice, so the boy was taken to the Etihad Stadium where he met with security staff and resolved the matter.'