The Italian player scored the second goal in Saturday's 2-0 victory over Bolton Wanderers in the Premier League but Mancini hinted that if he had been aware of the incident plastered across the back of The Sun newspaper he would have left him out.
"Missing four or five chances because he went to sleep very late," Mancini told Sky Sports when asked about Balotelli's performance against second from bottom Bolton.
"I have not read the newspaper. Tomorrow I will speak with him. I am disappointed. If it is true I will fine him the maximum we can.
"We prepared the game with Mario, he was fresh, but the next time he will go in the stands. I don't like it because it is not correct, professional behaviour."
Saturday's fixture was the first game back for Balotelli after serving a three-match ban.
The striker has been involved in a series of on and off the field troubles since joining City in August 2010.
Mancini, though, was happy with a 19th consecutive home league win that put the leaders five points clear of second-placed Manchester United at the top of the Premier League.
"Today was important because we have taken three points and we need to keep winning because Manchester United are very good," said the manager.
"If we could win the next 10 games we would win the title. We just need to keep playing the way we are and we will have a very good chance."
