Balotelli was dropped for the 2-1 defeat of Tottenham and watched from the stands after not even being given a place on the bench.
Mancini insists the mercurial forward was left out for footballing reasons after poor performances in training.
He said: "Mario didn't play because it was my choice. I have 20 players and if there are some players that don't work well, they don't deserve to play.
"Mario is like the other players. There were other players that worked better than Mario and they deserve to go on the bench or to play."
Since last weekend there have been fresh reports linking Balotelli with a move back to Italy in January.
The player's agent quashed that by saying the 22-year-old would see out the remainder of his contract and that his relationship with Mancini was like that of a married couple.
Mancini said: "I know Mario like a guy, like the other players but I am a manager, he is a player.
"If he doesn't work well, he doesn't play. Like the other players, nothing changes.
"He is my player. Sometimes he plays well, sometimes not well but he is an important player for us. We don't think of selling him in January."