Fabregas, who used to be Arsenal's captain, left the club to join Barcelona in 2011 before moving to Chelsea in 2014.
Arsenal fans were infuriated when Fabregas joined Chelsea since he said that he would never join another Premier League club when he left the Gunners.
"I want every player to be respected and for Cesc Fabregas, when he comes to the Emirates on Sunday, to be respected because he deserves it," Wenger said during a press conference. "He is a great player. It is difficult for every player who has played almost every game this season to be at the top of his game every game, but he is a great player."
Wenger also looked a bit uneasy when asked whether he regretted not convincing Fabregas to return to Arsenal after his stint with Barcelona.
"Look, the regret I have is that he wanted to leave here," he said. "This club and myself had a very positive on Cesc's life, so it is a bit uncomfortable trying to justify myself why he is not here today."