Ronaldo also claimed other clubs were interested in signing him from Juventus last year.
But the 37-year-old insists he followed “his heart” and rejoined the Red Devils.
“Well, honestly, it [moving to City] was close. They spoke a lot, and Guardiola said two weeks ago that they tried hard to have me.
“But, as you know, my history is at Manchester United. Your heart, you’re feeling the way you did before, and it made the difference. And of course, as well, Sir Alex Ferguson.
“So I took the decisions and I repeat: I was with conscience that it was a good decision.
“Things changed around in 72 hours. You plan or they spoke, not only Man City but other clubs too. Man Utd wasn’t part of those teams but it surprised everybody, even me,” Ronaldo said.
Ronaldo, in the initial episodes of the interview with Piers Morgan, claimed he felt “betrayed by the club”.
He also made it clear he has no respect for manager Erik ten Hag.