The former England captain's contract with MLS side Los Angeles Galaxy ends in December, which has led him to be linked to a number of clubs.
"It's a difficult one," said Redknapp. "You would love him around your football club. As I have said many times, you couldn't get a better professional and a nicer guy.
"But he wants to play and it would be difficult because I have a lot of players here at the moment in those sort of positions, so it wouldn't be easy.
"But who knows? Let's see what happens when David's contract runs out."
Spurs travel to Newcastle United in the Premier League on Sunday.