Ronaldo, 37, is pushing to leave the Red Devils in search of Champions League football.
Speaking on Rio Ferdinand's VIBE WITH FIVE Podcast, Nani said: "It's a long time since we played together and Cristiano is not a kid anymore.
"Times change and the reactions and attitude can change as well. But, as we see, he's doing the same things as usual; he doesn't like to lose, he reacts when the team is not doing well.
"But the only difference is that it's different times. He's playing again at Man United but he's been all over the world doing well at different teams with different players. He's in a team where the managers are trying to build a strong team and it's not easy, it takes time.
"For Cristiano, he doesn't have time to lose on building teams or waiting for the next season. He wants to continue to be at the top, scoring goals, being the man. That's why the reaction is normal, we all have the wrong reactions sometimes."