Arshavin came off the bench to help create Arsenal's winning goal against Queens Park Rangers last weekend in a rare Premier League appearance.
Wenger believes that the Russian playmaker is still capable of making a meaningful contribution for the Gunners this season.
He told the club's official website: "Andrey comes in every day and practices well, he is focused and wants to do well.
"I insist on this, because it was questioned and it is completely unjustified. In this case perception is not reality.
"He is a classy player and a top professional with a great attitude. You could see that when he came on [against QPR], his brightness and his intelligence with the final ball is fantastic."
The 31-year-old is in the Arsenal squad for Tuesday night's League Cup tie against Reading after scoring in the last round against Coventry City.