The Belgium international has four years left on his current deal, and back in July he suggested he would like to extend that agreement.
However, Vertonghen has found first-team opportunities hard to come by early weeks in Mauricio Pochettino's reign, and the 27-year-old announced on Thursday that he would not be signing new terms with the club.
"I am not signing, no," he is quoted as saying by the Tottenham and Wood Green Journal.
"We agreed not to. Why? I would prefer not to say. I still have four years left.
"I am happy at the club and I think they are happy with me. That's where it ends.
"I am very happy. We have a good manager, we have a good team and a lot of good players. The squad is very big and you have to work hard to play every game, and I hope I am playing again soon.
"It is good [under the new manager]. He is working well with a lot of videos and individually he talks a lot with the players.
"He is a manager who expects a lot from players. We work hard and that is good - it will pay off in the end I think."
