The 23 year old is out of contract at the end of the season and talks over an extension have so far failed to reach a conclusion.
Wenger said: "I don't think you can put a timeframe on when it will be resolved. Ideally he has to commit. It is difficult. I believe you have to commit at some stage.
"It is very important in our sport to be very committed to where you are, and as long as you do not do that, you are not completely at ease. It is important for our squad as well that he is completely committed.
"I do not doubt it, but as well at some stage it has to be concrete."