Speaking on Wednesday, Perez said Madrid had chased Lewandowski and were experiencing similar in their pursuit of Pogba.
"There are players who do not sell," he said, via Spanish media.
"For Lewandowski, we have gone for several years for him and nothing because he has no clause and they don't sell him.
"There is no way and that has happened to us with Pogba. When certain players are sold, we can go for them."
Perez was coy when asked about the France international, who is widely regarded as the best young talent in the world.
"Of course we like a Frenchman that they say out there and we'll go for him," he said. "But they don't sell him."