The Croatian playmaker recently insisted that he wanted to stay at White Hart Lane to boost his chances of Euro 2012 selection.
"They have no chance. I wouldn't sell Niko to anyone. He is far too important a player for me," Redknapp told reporters.
"In the long term, who knows? If he doesn't play next year and wants to go, I maybe wouldn't stand in his way as I like him so much, but we don't want to let people go who can help us."
Kranjcar has made six Premier League appearances for Spurs this season.