Former Arsenal defender Martin Keown also believes the Portuguese manager is at war with his players.
Mourinho's relationship with the Frenchman is at rock bottom after telling the midfielder he will not captain the club again.
It comes after Pogba told reporters that United should be attacking more after their 1-1 draw against Wolves.
Mourinho admitted to Sky Sports that there was "no problems at all" with Pogba but Redknapp is not having any of it.
Redknapp said: "There's been an almighty fall out.
"That's a kick in the teeth if you tell someone they are the vice-captain and then you take it off him. You don't need me to say it.
"There's a huge rift between the two of them. I felt they might be able to recover it when Mourinho made him captain for a couple of games.
"I think it was probably the right decision to rest him today, but going forward I don't see how you patch that up."
Redknapp also said the board would favour the player over the manager.
He added: "You can sack Jose Mourinho, but you can't sack Paul Pogba. What are you going to do with him?
"I've been in dressing rooms where the manager has lost the players and all you get is cliques. Players will get into their corners.
"That's how I see this Manchester United dressing room. I can visualise it now. There's so many unhappy people."
Keown echoed Redknapp's views that Mourinho is not a popular man in the dressing room.
He told BBC 5 live: "Jose seems to be at war with his players and he needs to start seeing the good in what they do.
"Is he pulling up the handbrake?"
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