The Black Cats have been busy strengthening their squad this week and the arrival of David Vaughan on Friday took the number of summer signings to nine.
Reports had also suggested that Defoe and N'Zogbia could be on their way to the Stadium of Light in the near future.
Defoe's future has become the subject of speculation after he admitted his frustration at a lack of regular starting opportunities with Tottenham last season.
N'Zogbia has also been linked with a move away from Wigan despite manager Roberto Martinez expressing confidence that he will stay.
However, Sunderland are now understood to have informed Sky Sports News that they have no plans to make a move for either player.