The controversial striker was hauled off 30 minutes into City's pre-season friendly with LA Galaxy on Sunday night for failing to take the game seriously.
The Italian youngster fired Macini's side ahead in the 20th minute with a penalty after a foul on Micah Richards, but 10 minutes later he was substituted following a bizarre incident. After being put through on goal, Balotelli decided to drag the ball back before backheeling it wide of goal.
The episode did not go down well with boss Mancini and he immediately called the 20-year-old back to the bench.
"I hope this is a lesson for him," Mancini said after the game.
"In football you always need to be professional, always serious and in this moment he wasn't professional.
"If you are serious, you can play 90 minutes. If not, you can come and sit by me on the bench."
The Premier League big spenders won the game 7-6 on penalties after it finished 1-1 in normal time, but all the talk was about the Balotelli incident.
The former Inter Milan player exchanged words with Mancini after he was taken off and also threw his water bottle onto the floor. Balotelli failed to return to the dug-out after the half-time break.
"He needs to understand his behaviour has to be good in every game - not just in a final or a semi-final but every game," the 46-year-old tactician added.
"He knows he made a mistake. Football should always be serious and if you have a chance to score, you should score.
"Mario is young, I want to help him and that is the end of it. To take him off after 30 minutes is enough punishment. It won't have been easy for him but it has to be a lesson."
Asked what Balotelli said to him, Mancini replied: "It was in Italian. In English I would find it difficult to give you the translation. But Mario is streetwise, he knows he was not offside."
The player has already been involved in several incidents since his high-profile £24million move from Inter last season.
He threw a dart at a youth-team player last March and also angered several Manchester United players after he taunted the crowd following City's win over their neighbours in the FA Cup semi-final at Wembley.
The Italian youngster fired Macini's side ahead in the 20th minute with a penalty after a foul on Micah Richards, but 10 minutes later he was substituted following a bizarre incident. After being put through on goal, Balotelli decided to drag the ball back before backheeling it wide of goal.
The episode did not go down well with boss Mancini and he immediately called the 20-year-old back to the bench.
"I hope this is a lesson for him," Mancini said after the game.
"In football you always need to be professional, always serious and in this moment he wasn't professional.
"If you are serious, you can play 90 minutes. If not, you can come and sit by me on the bench."
The Premier League big spenders won the game 7-6 on penalties after it finished 1-1 in normal time, but all the talk was about the Balotelli incident.
The former Inter Milan player exchanged words with Mancini after he was taken off and also threw his water bottle onto the floor. Balotelli failed to return to the dug-out after the half-time break.
"He knows he made a mistake. Football should always be serious and if you have a chance to score, you should score.
"Mario is young, I want to help him and that is the end of it. To take him off after 30 minutes is enough punishment. It won't have been easy for him but it has to be a lesson."
Asked what Balotelli said to him, Mancini replied: "It was in Italian. In English I would find it difficult to give you the translation. But Mario is streetwise, he knows he was not offside."
The player has already been involved in several incidents since his high-profile £24million move from Inter last season.
He threw a dart at a youth-team player last March and also angered several Manchester United players after he taunted the crowd following City's win over their neighbours in the FA Cup semi-final at Wembley.
