Redknapp is keen to hold on to the 25-year-old, who enjoyed a superb season at the heart of the Spurs midfield last year.
The 64-year-old Redknapp recently described Modric as "irreplaceable" in the wake of reported interest from Chelsea, and the Londoners are understood to have had a £22million offer for the Croatian playmaker rejected on Wednesday night.
"Luka is not for sale," Redknapp told the BBC.
"If there has been a bid of £22m, that is ridiculous. There are people being sold for £20m who are not fit to lace Luka's boots."
Modric joined Spurs from Dinamo Zagreb in 2008 for £16.6m and has played 120 games and scored 12 goals. He signed a new six-year deal at the club last year.
Earlier this month Modric told a Croatian newspaper that he was happy at Spurs but would be open to a move if the club altered their stance and chose to sell him.
"If an offer comes which is good for Tottenham and for me also, then a transfer is possible," said Modric.
Source: AFP
Source: AFP