But Vermaelen ended up signing a new long-term contract with the Gunners in October.
"I thought about the situation with my contract for a really long time," said the centre-half.
"Of course, I knew there were doubts from outside about the club. But the most important thing for me is that I feel happy here.
"I have only really played one year of games at Arsenal, so I wanted to give something back to the club that has looked after me.
"I believe in the club, I think the structure is really good. They are the main reasons I stayed.
"I think we can challenge the other clubs like Man City and Man United. We have to look at ourselves and we had to do that when our start wasn't perfect."
He added: "We didn't have a great start to the season. We were in a situation where we had to fight for every point.
"You can see that we are doing that and we are €improving as a team and our organisation is better.
"If the shape of the team is good you can defend well. If the shape of the team is good you can go for victories and when you have Robin van Persie scoring in every game it's good for us.
"It's four weeks since I played my first game after coming back from injury.
"It was frustrating to be out for most of last year and to have another injury at the beginning of this season. These things happen in your career and you have to be strong mentally to get through.
"If you work hard you get the reward. I feel good now and I feel very much part of Arsenal.
"When I was out and the team was being criticised, well, that was no fun. But that is part of football - you get difficult periods. Yet step by step we are getting better. I hope we can keep improving.
"We are doing okay but it's not perfect. Other teams will also do well and it will be a tough year."