Speculation has suggested that the ex-Chelsea boss will take the reins at Old Trafford when the 71-year-old Scotsman steps down from his tenure at the North-West club.
"I'm not sure if Alex Ferguson will leave United in the hands of Mourinho, as rumours have suggested," Wenger wrote in his column for Eurosport.
"I don't think it will be Ferguson who will decide who replaces him. We can perhaps ask his opinion, but it is not necessarily his job to think about that."
Meanwhile, Ferguson will go up against Mourinho for tonight's Champions League first-leg clash against Madrid at the Bernabeu.