But his manager will investigate reports of a night out on Thursday.
"I didn't read the newspapers," Mancini said. "Tomorrow I will speak with him. If everything is true I will do the maximum fine that I can do."
Balotelli's goal was his second since returning from a four-match suspension after an alleged stamp on Tottenham's Scott Parker last month and his 14th goal of the season.
"I'm really disappointed," said Mancini when asked about the 21-year-old's most recent alleged transgression.
Destiny 'in our own hands' - Coyle
"But I need to speak to him because I don't know what or when it has happened. I will [stick with him] because he's a good player but, if it is true, I will speak with him tomorrow and decide about the fine.
"Maybe if he goes to bed earlier, maybe he scores three goals [against Bolton]. Maybe he missed four goals for this reason."
Balotelli joined City in a £24m deal from Inter Milan in the summer of 2010 but has been involved in a number of controversies on and off the pitch.
He has been sent off three times, was unable to continue after suffering an allergy to the grass in a game in Kiev, threw a dart at a reserve team player and escaped injury after a firework was let off in his house.
With closest rivals Manchester United facing a tough trip to third-placed Spurs on Sunday, Mancini was pleased to gain another win as he rested David Silva, Sergio Aguero and Micah Richards after a round of international friendlies in midweek.
But the Italian said his team needed to be more clinical.
"I'm happy for our performance. When you play a team fighting against relegation it is difficult," he added.
"We missed five or six chances to score in 10 minutes. This can be a problem sometimes. We were unlucky because their goalkeeper did very well and maybe we should pay more attention.
"When we have a chance to score it's better to score quickly."
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