Ronaldo has been at the centre of intense gossip about his future after revealing following Madrid's home win over Granada earlier this month that he did not celebrate his two goals in the match because he was "sad" for professional reasons, but without elaborating.
The Spanish media were quick to suggest the 27-year-old, who has scored 150 goals in 149 matches for Real since his world-record £80million move from Manchester United, was eager to leave the Bernabeu, while his desire for a new improved contract was also mooted as a possible reason for Ronaldo's discontent.
The Portugal star has twice taken to Facebook to deny the contract suggestion but that has only led to more talk about what has caused his misery.
Asked about the situation at Friday's pre-match press conference for Saturday's league trip to Sevilla, Mourinho said: "I'm a football coach and at this moment the only thing I'm concerned about is that my team still haven't played well.
"If Cristiano's sad and he plays like he plays, then that's perfect for me.
"Cristiano works at 100%, plays at 100%. At times he does better and other times worse. He cannot be the match-winner in every game but he's always a team player, who in every training session and in terms of discipline is exemplary.
"I don't have to worry about things that for me are supplementary and not fundamental."
Mourinho also urged the media and public to judge Ronaldo on his performances and not speculate on other issues.
"I think you (media) have had 15 days to speculate because there hasn't been any football or special international matches.
"Now Cristiano needs peace and tranquility to play football, which is what he knows and likes most.
"You, the Bernabeu and the public, we must evaluate his performances on the pitch and nothing more.
"If tomorrow [Saturday] in the 75th or 80th minute he has played a horrible match, or he's tired, then he'll be taken off and someone else will come on, that's how it is."
Madrid travel to Sevilla lying 11th in the standings after a sluggish start to the defence of their title, which has seen them held at home by Valencia, lose at Getafe before finally claming their first win with that triumph over Granada.