Modric missed Tottenham's 3-0 defeat against Manchester United on Monday after Redknapp decided the player was too unsettled by all the transfer talk to focus on the clash at Old Trafford.
Chelsea are believed to have made an improved ?30 million ($49m) offer for Modric after having two previous bids rejected during the close season, but Spurs chairman Daniel Levy is determined to keep the playmaker.
Redknapp met with Levy on Tuesday to discuss the situation and was again told that the Croatian is staying.
Modric did not train with his team-mates on Wednesday morning, but could play in Thursday's Europa League play-off second leg against Hearts if Redknapp thinks he is focused enough.
"The situation is that he is not for sale," Redknapp said. "Yesterday when I spoke to the chairman, he said Luka definitely wasn't going and that was the end of the matter as far as he was concerned.
"Luka has to get on and play now. I need him back playing. Will he play tomorrow? Possibly.
"We will see how his hamstring is on Thursday. Certainly I'm looking to have him fit for the weekend against Man City."
Playing Modric in Thursday's clash -- which Spurs lead 5-0 from the first leg -- would mean he would not be able to play in the Champions League for Chelsea until February if he moves, but Redknapp is not worried about that.
"We are not in the Champions League so it won't affect us," Redknapp said.
"I'm not bothered about anyone else. He is here, we love him, he is a great player so I need him back playing. He has to crack on with it now and I'm sure he will."
Redknapp also said he would block Modric's participation in Croatia's Euro 2012 qualifier against Malta next week if he continues to miss Tottenham's matches.
"He is not going to go away and play for his country next week if he doesn't play for Tottenham," Redknapp said.
"Like all players, if they are not fit to play for their clubs they will not be going off on international duty."
Redknapp is also hoping to seal a loan move for Manchester City striker Emmanuel Adebayor and he believes Spurs fans will ignore the fact that he used to play for their hated rivals Arsenal.
"He is a good player and he is a real talent," Redknapp said. "If we can get him at it he could be a big success as he has a big point to prove.
"People have played for both teams (Arsenal and Spurs) before. William Gallas came in here last year and did well for us and the crowd took to him.
"If he (Adebayor) comes here and gets goals the fans will love him. If he doesn't, they'll slaughter him."
Source: AFP
Source: AFP