The Spain midfielder was again absent from the squad for Saturday's final pre-season friendly against Benfica in Portugal.
Wenger: "He is just coming back from injury and is not ready to play in a game, but he is not injured.
"I don't think Fabregas will be ready to start the season because he has been out for a long time and has had no games."
The Gunners travel to St James' Park next Saturday.