Vermaelen has made just six appearances for the Barclays Premier League leaders this season, with Laurent Koscielny and Per Mertesacker the preferred centre-back partnership.
Wenger, who has denied reports linking him with moves for strikers Alvaro Morata and Alexandre Pato, is impressed by the way the Belgium defender has dealt with his lack of opportunities.
"It's tough to leave Vermaelen out because of his quality, his attitude and his influence at the club," the Frenchman said.
"It's a difficult decision to make because he is a top-class player.
"He certainly suffers but he handles it with great dignity and great professionalism.
"I'm not concerned that he might move in January because if he wants to do that he will come and see me, which he has not done."
Arsenal are hoping to extend their four-point lead at the summit of the Premier League when they host Hull on Wednesday night.
Bookmakers predict a three-way tussle for the title, with Manchester City, the Gunners and Chelsea competing for honours in that order.
However, Wenger believes it is unwise to dismiss the challenge from Manchester United, who are nine points below first place.
"The bookies have an opinion that you can understand because they just look at the table," he said.
"But I wouldn't rule some other teams out like Man United. It's a bit early to make any prediction on the championship.
"What is more at stake for us is consistency that we have shown until now."
Instrumental in Arsenal setting the pace in the title race has been the stunning form of midfielder Aaron Ramsey, who has struck 13 goals in 21 matches.
Wenger believes his performances have justified his decision to offer Ramsey a new contract last year, despite his previous mixed form, and insists the best is yet to come.
"At the time I had no doubt. I always felt he had a good attitude, good basic qualities and will come out of that bad patch in a strong way," he said.
"Don't get me wrong, I didn't predict he would score as many goals as that but I was always confident he would make a good career.
"When you are a midfielder you want to defend well, you want to attack well and you want to give assists and score goals. That is how good you can be.
"At the moment he does all of these four things very well and he can still improve."
Wenger is puzzled by Hull owner Assem Allam's attempt to rename his club 'Hull Tigers'.
"I don't think why it should happen and I don't know exactly what is behind the thinking at Hull. I don't understand it," said the Frenchman.
"Usually there is a tradition that is linked with the name of the club that people want to keep.
"Overall, I think the difficulty in the modern way of thinking is the respect of tradition and forward thinking - you have to combine both. The name is usually part of the tradition."