The Morocco international has been linked with a January exit.
"The most difficult thing for a player is first the competition he faces - and Chamakh has faced the competition of Van Persie," said Wenger.
"Secondly, if you do not play regularly, every time you play you have to be outstanding.
"He is more a player who works for the side, so he needs the confidence. He is not a guy who does something special, he is more a guy who needs to be in there every week. That's why I believe he suffers a bit from the lack of chances he gets."