The former defensive midfielder was a part of the Class of 92 at United, which went on to win the Treble.
Butt was asked about Ronaldo’s talent, who came through at United as Butt’s time at the club was coming to an end.
On talkSPORT, Butt said of Ronaldo: Butt said: "He wasn't when I was there because he had so many little flaws he had to deal with.
"Dribbling, too much diving. I remember him getting abused in training every time he would dive off the more experienced pros. 'Get up. You don't do that.' You know, 'You never dive at this football club.'
"It's like the story of Ole Gunnar (Solskjaer) when he dived over the Newcastle player running through. You have to do it the right way.
"I knew he'd have the talent to get there, but getting talent is different to actually doing it.
"You have got to be a really top, top human being to be a top, top player in my opinion."