Vermaelen, who replaced the injured Laurent Koscielny in the Arsenal defence, was keen to stress that the current squad should be able to succeed with their teammates on the sidelines.
"Of course we're missing players but we have a big squad with lots of players so that shouldn't be the reason," the Belgian told Sky Sports News.
"I don't think there was a lack of confidence in the team. We were pushing the whole game and we had most of the possession. We tried very hard so in the end it was a disappointing result."
Arsenal are currently fourth in the Premier League with seven games remaining.