Modric has been a key part of Tottenham's success since Redknapp signed the Croatian from Dynamo Zagreb in the summer of 2008.
"He (Modric) is such a fantastic player if we start selling such a player like that then we might as well all go home," Redknapp said. "He is a different class and is not going anywhere. Not a chance."
The midfielder, who signed a new six-year contract in May after reported interest from Manchester United, is thought to be on Chelsea's radar although Blues manager Carlo Ancelotti has played down suggestions he will make a move for the 25-year-old in January.
Redknapp ridiculed the suggestion that Modric will leave next month, insisting that the midfielder will have to stay at the club if he is to fulfil his aim of making Spurs a team capable of becoming Champions League regulars.
"He (Ancelotti) might have his eye on him but he is not going to get him for sure. He is a pleasure to work with. He is a fantastic player. We are building a team here, not dismantling one."
Keane's future now looks certain to be away from Spurs after Redknapp admitted the Republic of Ireland hitman is growing tired of his lack of first-team football.
Keane, who was loaned to Celtic last year, has been linked with a move to West Ham, Aston Villa or Birmingham, but Redknapp denies there has been any interest in the 30-year-old yet.
Redknapp said: "Robbie would like to move and he wants to play. He is a boy who has played all his career. He is not used to not playing.
"He is still a top player and would grace most clubs. It's just that he has been unfortunate with Rafa (van der Vaart) coming in and I've been playing one up with him. I have Defoe, Crouch, Pavlyuchenko and Robbie so it's been difficult getting him in the team. I haven't heard anything about any offers for him though."
Source: PA
Source: PA