The Blancos chief has hinted the goalkeeper will remain at the club and refused to hit out at Gerardo Martino for criticizing the record sum spent on Gareth Bale.
Los Blancos have started the season with Diego Lopez as first-choice goalkeeper, just like he was in the second half of the last campaign, but Perez cast doubt on the skipper being shipped off in the winter.
"It'll be difficult for him to leave in [the next transfer window]," Perez told Cadena SER. "Mou's decision on dropping Casillas was made for sporting reasons. He gave him a little warning and then after that it was because he was injured.”
The Santiago Bernabeu chief refused to hit back at new Barcelona boss Gerardo Martino for criticizing Madrid's reported 100 million euro purchase of Gareth Bale, suggesting that the Argentine is not used to the big-spending culture in Spain.
"Martino is new to his post and he doesn’t know very well how signings work here," Perez said. "It's easy to agitate public opinion."
Madrid's brought in Carlo Ancelotti to replace Jose Mourinho over the summer and Perez revealed the Italian had to be pried away from Paris Saint-Germain with a contract nearly identical to that of the departing Mourinho.
"We paid PSG 7 million euros for him," Perez said. "We paid one half and he paid the other. He earns more or less the same as Mourinho."