The midfielder left the club in the summer to the dismay of his manager, who insists "you want to keep your young players" and admits he was forced to sign new recruits
The French playmaker swapped London for Manchester after refusing to sign a new deal, angering many fans of the club, who also saw Cesc Fabregas depart for Barcelona over the summer.
However, Wenger is hoping his former employee is given a positive reception on Tuesday evening when Manchester City play Arsenal and says Nasri improved greatly as a Gunner.
“I hope Samir gets a good reception," Wenger told Arsenal Player. "I don't know if he will play but personally I want every player who has played for us to be respected when they come back.
"Samir improved tremendously while he was with us. He has developed fantastically well from a non-scoring player to a guy who could make a decision. Of course he was an important player here and I'm sure he will be for Man City as well.”
Wenger admits he wanted to keep Nasri with the player being such a prospect for the future and says he had to sign more players in reaction to the midfielder’s departure as well as the long-term injury to Jack Wilshere.
“You want to keep your young players but when we didn't reach an agreement over a new contract I prepared myself to face it [the prospect of Nasri leaving]," Wenger added.
"Overall I knew that [Aaron] Ramsey didn't play much last year and that he would be in contention if he had a chance not to be injured. In pre-season I felt that Wilshere and Ramsey worked very well together.
"What we did not expect of course was to lose Wilshere on top on that. We had to admit then that we were a little bit exposed quality and number-wise [so we signed more players].”