The Welshman has been linked with a big-money switch this summer after a sparkling Premier League campaign when he was crowned Player of the Year.
Real Madrid are interested in signing Bale and Zidane, sporting director at the Santiago Bernabeu, has reiterated that they would not be afraid to spend heavily to secure his services.
But the Frenchman also thinks that Bale could speed up the process by speaking to his club bosses and requesting a departure.
"I think Real Madrid have made their admiration of Gareth Bale very clear - and it has been made clear that we would not be put off by the cost of the player," Zidane told the Sunday People.
"But if Gareth feels now is the time to move then he has to have a private discussion with his club and express that he wants to leave."
Tottenham's failure to qualify for the UEFA Champions League increased the speculation about Bale's future and his agent recently refused to rule out a move to Spain.
However, Bale has always been quick to declare how happy he is at White Hart Lane and has previously spoken of how much he enjoyed playing under Andre Villas-Boas last term.