The French forward joined the Catalan outfit from Atletico Madrid in 2019, but was only able to register nine LaLiga goals all last season.
Barcelona manager Ronald Koeman will continue to use Griezmann on the flank, but Wenger feels that will be a problem.
"Not playing at his position is complicated in the long term," Wenger told beIN SPORTS.
"At the start, the guy accepts it but, if he does not meet his needs in the long term and he feels that the position does not allow him to express his qualities, he will become discouraged.
"Today, he is a player who must play in the centre because he has a great work rate, a precision in his passes.
"He can be dangerous with the last pass and by scoring goals, but there is congestion because he is in the range of play of Messi."