The Portuguese winger is currently serving a three-match ban following his dismissal for an apparent headbutt on Pompey's Richard Hughes in the Fratton Park clash.
The champions have picked up just two points from their opening two games, and will now be stripped of their star man's talents for the games against City, Tottenham Hotspur and Sunderland.
But while Sir Alex Ferguson was quick to condemn any reaction from his players, Ronaldo refused accept the red card he was given was justified.
"The replays show there was nothing," Ronaldo told the Sun.
"But I don't need to look at the pictures, because I know exactly what I did - and that's nothing to justify a red card."
Ronaldo was eager to point out he did not headbutt Hughes in their coming together.
"I was pushed in the area. He came straight to me, put his hand on my neck and I opened my arms in a 'that's enough' way. We pushed each other but nothing serious," he added.
"We leaned heads against each other but that was all. Absolutely nothing else happened.
"When I saw the red card, I couldn't believe it, the situation was so surreal.
"And it's absurd because I'm aware that now I'll sit out a ban for something I didn't do. I feel dejected and very sad."