Both Toronto FC's Defoe and Los Angeles Galaxy star Keane have played for Redknapp.
"We've not made an inquiry for Robbie Keane. I've not spoken to Jermain Defoe either," Redknapp told Sky Sports News in England.
"Robbie's an amazing footballer, one of the best professionals I've come across. He's gone over there and been the best player in the league, he hasn't gone there for a holiday but he belongs to the L.A. Galaxy and is the star man of their team and league. We've never made an inquiry about him. They wouldn't let him go.
"I've never spoken to Jermain. I asked about him in the summer, but he was too expensive and the club wouldn't let him go anyway. He's a top player."
Redknapp did say his club needs to add players in January.
QPR (4-9-2) currently stands 17th in the Premier League, just one spot ahead of the drop zone.
Reports have suggested QPR is interested in bringing Keane in on loan during the MLS off-season. Defoe's future in Toronto has been under a cloud since the MLS club turned down a franchise-record transfer offer in the summer.
Defoe is currently recovering from surgery to repair a groin injury.