Ramos' deal expires in June and talks over a new contract have dragged on for months.
Perez said, "In Madrid nobody puts the money and you have to be realistic with what happens. I have not said that Ramos will not continue. We are looking at how to fix the closure of this season, and we will see what comes next.
"Many things can happen, we are going to close this season, we are talking with sponsors and players about lowering their salary.
"There are people who are in solidarity with the club. Sergio Ramos last year his salary was lowered and this year he is in a different case."