The French midfielder is suffering with a groin injury and has not featured for the Premier League champions since September's defeat to Bayern Munich in the UEFA Champions League.
Nasri has since undergone surgery and Pellegrini is hopeful the 27-year-old can be back in team training next week.
"Samir Nasri is recovering from his surgery," the Chilean explained.
"I don't know exactly but I suppose that end of the next week he will start working with the whole team again."
Nasri has made six appearances for City this term but is yet to score, however his return could potentially come in time for the Manchester derby at the Etihad Stadium on November 2.
Following Tuesday's Champions League clash with CSKA Moscow, City take on West Ham and Newcastle United before facing rivals Manchester United.
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