Ronaldo has scored 355 goals in just 339 outings, but having recently turned 31 and with injuries starting to creep in, there have been suggestions that Los Blancos will look to cash in during the summer.
However, ex-Madrid winger Gento has insisted that there is no way the club should consider selling the Portuguese attacker.
"How are you going to sell a player who scores so many goals for you every day," he told La Galerna.
"No, man, no. Plus, Madrid have never been a selling club, Madrid above all have bought players.
"Madrid should not sell, they should buy. Cristiano knows the people here, and the club love him."
Ronaldo is expected to feature for the Spanish outfit in their Champions League game against Wolfsburg tonight.