Both players have been heavily linked with a move to Loftus Road with their respective contracts at Chelsea and Manchester United expiring this summer.
But Redknapp, speaking on Tuesday at the launch of QPR's new kit, said: "I would think there's absolutely no chance of getting Frank. He's at Chelsea.
"I'd be very surprised if Chelsea don't keep him anyway - he's just been such a fantastic player.
"Rio's now a free agent but I'm sure he's going to have so many offers.
"Again, I love Rio, I signed them both as 15-year-olds but the chances of getting them to QPR are very slim."
Ferdinand was once the world's costliest defender when he moved from Leeds to Manchester United in 2002 for £30m, but is now available on a free transfer after his Old Trafford career came to an end.
Lampard joined Chelsea for £11m in 2001 from West Ham, the club Redknapp brought him and Ferdinand to as teenagers.
The QPR boss also admitted it would be difficult to keep Loic Remy at the club.
"Loic has done well at Newcastle," he said. "It would be difficult to get him back here. I think he's looking to play Champions League next year somewhere.
"He's had a great season at Newcastle - he's certainly worth much more than we paid for him when we brought him here."