The 30-year-old has responded with seven goals in four cup games, but believes that he must play in the league to remain part of Roy Hodgson's plans for Brazil next summer.
He told The Mirror: "To get into the squad that goes to a major tournament, you have got to be playing for your club. It is great to score in those cup competitions, but I feel you have got to be scoring in the Premier League.
"As you can imagine, it is very frustrating, especially after I worked so hard in pre-season and telling people I feel sharper and stronger than ever.
"Obviously you have a word with the manager. I speak to Andre and stuff like that. But I have got to play, it is a World Cup year."
In 54 appearances for his country, Defoe has scored 19 times, 12 of those goals coming in 22 international starts.