Wenger confirmed Walcott will be out for up to six weeks after damaging his ankle ligaments during England's 3-1 win in Switzerland on Tuesday.
And the Frenchman insists the winger, who appeared to be finding some form at Arsenal, will bounce back from to another injury setback.
Wenger said: "It was a bad tackle on Theo and now I hope these injuries do not harm his confidence in the box or in his tackling.
"You never know what kind of psychological impact it has on the player.
"In our job it is important you are healthy and you play.
"When you are injured, it always stops your progress and sets you back when you do not have regular games.
"The mental side is always a question mark when a player get injuries. However, I believe Theo will deal well with that because he has done it before."