The club's development executive admits that the 25-year-old has had a lacklustre campaign, but says the ensuing criticism heaped upon his shoulders belies his undoubted quality
Nasri has found the net just once in the top-flight this season and has been unable to hold down a position in the starting lineup, drawing criticism from manager Roberto Mancini.
However, after some better displays - including a goal against Chelsea in the FA Cup semi-final, Vieira insists that Nasri still plays a major in the set-up at the Etihad Stadium and says that the midfielder will be a better player next year.
"All of these problems have perhaps sullied the image of the player, however, he remains an important player for City and the France national team," he told RMC.
"The insults are unacceptable. I hope he will stay even if he had a tough year. Samir is in his position among the best players. Samir could do much more this season.
"He is disappointed with his level but he remains central to the dressing room. I see it every day, he learned a great deal. He will be much stronger next year."