Spurs finished fifth and will play in the Europa League this coming season.
Defoe said: "I felt like we had a good season in terms of points and the way we played. To miss out at the end was so hard to take not only for the players but for the manager who came in and was fantastic. It means so much to the whole club and the fans, and they deserve it. They were great last season.
"On a personal note, I’ve been there a long time and I want to achieve things for the club. I want to play and score goals in the Champions League, so it was really difficult. It was hard. That’s why we’re looking forward to this season so much. Sometimes in life when you have something to fight for you get the best out of yourself."