Moyes replaced Sir Alex Ferguson in July but is struggling with United currently seventh in the Premier League.
"When a person has been at a club for such a long time, it's always a void created when he goes," said Wenger.
"But I believe Moyes, if given time, will do that perfectly."
United take on second-placed Arsenal at the Emirates on Wednesday with 14 points between the two sides, and the Old Trafford club are nine points off the Champions League places.
"You need time and patience," said Wenger. "You need to be in a strong club. [Moyes] is in a strong club and I think he will be given time to do it."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball