Nasri has started three of City's past four matches, only missing the League Cup tie against Wigan on Tuesday, while the 26-year-old midfielder was arguably his team's best player in their 4-1 demolition of Manchester United in the Premier League last week.
The talented playmaker has earned a reputation as a frustrating player to coach with former City manager Roberto Mancini having once claimed he wanted to 'punch' the Frenchman, while ex-France head coach Raymond Domenech claimed Nasri was solely motivated by 'self-interest'.
But Pellegrini seems to have no issues with Nasri but has called on the Marseille-born man to show consistent form this season.
"At this moment, Nasri is playing very, very well," Pellegrini said.
"I talk often with him because I know how much he can be a big player.
"I am always wanting that level of performance from him and he knows he must play the way I know he can.
"If he doesn't, it may be that we have another choice (to make) but Nasri is absolutely committed with the team, with me, with all the other players. So we will be happy if we see a great Nasri the whole year.
"He is a player with great technical quality. He works the whole game a lot, not just the last 25 minutes, and he is a very creative player, a classy player."
Ahead of City's trip to Aston Villa on Saturday, Pellegrini has extended his challenge to Nasri to his entire squad.
City have failed to claim consecutive victories in the Premier League this season and Pellegrini has warned his players they must produce consistent wins or they will be unable to challenge for the title.
"Every team who wants to win something must demonstrate every week the intensity, the quality, the spirit we have here in this team," Pellegrini said.
"If you think you are going to win just with quality, then I think you are making a great mistake.
"I hope the team will continue trying to win every game we play but it's not easy. We are not going to win by four or five goals every week.
"It is very important for the team to win all the derbies, all the very important games.
"But also we are trying to improve our mentality and intensity in every game.
"Then our quality will maybe make a small difference."
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