Blackburn boss Sam Allardyce is said to be interested in bringing the 33-year-old Dutch striker back to the Premier League as he has fallen out of favour at Real Madrid but Redknapp has not enquired into the availability of the former Manchester United forward.
"He's a top player, if he's anywhere near fit I'm sure he can still play for a while but I've never enquired for him," Redknapp said.
"Sam's dug a few out like that over the years - he would come over here and score, he was always has done.
"I can see him going somewhere like Arsenal.
Tottenham is a big club - we shouldn't be afraid to compete with these clubs in the transfer market.
"But what would I do? I have Crouch, Keane and Defoe and Pav. If I got Van Nistelrooy, I give myself another problem."