Madrid were held to a 2-2 draw at the Santiago Bernabeu on Thursday after losing the first leg at the Vicente Calderon 2-0 earlier this month and Ronaldo struggled to hide his frustration with his side's early cup exit.
"Atletico don't play attractive football. They are very defensive," the attacker was quoted as saying by AS.
"They just wait for dead-balls. But it works well for them, so their coach and players should be respected."
The 29-year-old went on dismiss rumours that a knee injury is causing him problems again and stressed that people cannot expect him to excel each and every game.
"Goals aren't everything and players can't always be at their best. Unless you can tell me a player who always is at his best..." added the Ballon d'Or winner, who scored Madrid's second on the night.
"I'm not from another planet. Maybe I'm not in perfect condition, but I will be back.
"The knee issue is in the past, I'm used to playing with pain. In two or three weeks I'll be fine and so will the team."
Ronaldo has netted 36 goals in 27 appearances in all competitions for Madrid this term.