Sanchez, who is in the final year of his Gunners contract, came close to joining City during the summer transfer window, but the move broke down on deadline day.
The 28-year-old has continued to be linked with a move to the Etihad, with reports suggesting that City are preparing to make a fresh approach for the forward in the January transfer window.
Wenger insisted he was not worried that the transfer rumours would affect Sanchez's performance against City.
"I have no concerns because I'm not suspicious about performances or the desire to win of a football player," the Frenchman was quoted as saying by Sky Sports.
"When you are a football player you have a social contract with the rest of the team and I never question that. Once you don't respect that, it is difficult to say that you play football."
Sanchez has only netted twice for Arsenal in all competitions this season, but Wenger said he believed the forward is getting back to his best after a slow start to the season.
"I think he is coming back stronger physically. He runs after goals at the moment so he is a bit frustrated when he doesn't score like all the goalscorers," he said.
"I'm not worried about it, he works hard and it will come back. You never try too hard. I think at the moment he is marked well but he still creates many dangerous situations and he just has to not worry too much.
"You say that to all the strikers and they still worry but over longer periods he has always scored goals so that will come back."