He added: "I know we have a responsibility at Premier League level to set a good example to the whole football community.
"I am proud of my disciplinary record and have never been sent off in my professional career."
Ronaldo converted a penalty to win the game for United - after he had been tripped by Ball.
In an eventful game for the 27-year-old, Ball went on to win a spot-kick for his team when Wes Brown was adjudged to have brought him down but Darius Vassell missed the chance to earn City a point.