Spurs' asking price for Modric is £35 million
Croatia playmaker is a target of Real, PSG and United
Andre Villas-Boas has told Luka Modric will not be allowed to leave White Hart Lane until Tottenham's £35 million asking price is met, according to reports in the British press.
Modric remains a target for Real Madrid, Paris Saint-Germain and Manchester United.
Tottenham are resigned to losing their star midfielder this summer
But Villas-Boas said: "There has been continuous interest from three different clubs. But it's important for Tottenham to hold onto their rights.
"His situation will continue as it is until the price is right.
"Luka is an intelligent person and understands the club has to defend his value their values, rights and interests.
"But the offer has not been met to what the chairman wants. If that is met there won't be any problems."
Real Madrid striker Gonzalo Higuain hopes any deal to bring Luka Modric to the Primera Division champions will be wrapped up quickly.
Real are believed to be Modric's first choice move away from White Hart Lane after he failed to force through a switch to Barclays Premier League rivals Chelsea last season.
"I saw at Modric at Euro 2012 and also at Tottenham," Higuain told as.com.
"He is a player who loves the club and us. I wish to close the deal as quickly as possible if it is for the good of the team."
Real president Florentino Perez is looking to make a considerable offer after Tottenham chairman Daniel Levy rejected the £40m bid from the Chelsea last summer.