Buffon was sent off for dissent in the final minute of the quarter-final, second leg in Madrid after confronting English referee Michael Oliver over his decision to award the hosts a penalty in time added-on.
Angered by the decision, Buffon said Oliver had a "trash can" instead of a heart, while the 40-year-old dismissed the Englishman's ability to referee on the biggest stage - a tirade with which Del Piero disagreed.
Gianluigi Buffon said that he had no regrets over his outburst against the referees.
"I have a lot of respect for Buffon, the words he has said about me, and what I've said about him", Ronaldo told RTP, as cited by the Daily Metro. I need to search deep within myself and work out how I feel.
In the match, Juve overturned a 3-0 deficit, scoring three of their own unanswered goals, only for Oliver to award Real Madrid an injury-time penalty.
Ronaldo rescued Madrid against Juventus.
The 33-year-old official's family have endured serious abuse since the incident. Let the pitch do the talking.
The days he has had to consider his comments following Juventus' dramatic exit from the Champions League on Wednesday night have not changed much regarding Gianluigi Buffon's thoughts about referee Michael Oliver. It means you don't know where you are, what teams you face, what football is: "you don't really know shit".
Mario Mandzukic's two first-half headers and Blaise Matuidi's 61st-minute effort had helped the Italian side take a 3-0 lead at the Bernabeu, pulling them level on aggregate with half an hour left. I got emotional. It was just priceless.
"The team gave its all, but a human being can not destroy dreams like that at the end of an extraordinary comeback on a dubious situation".
In a game like that, 20 seconds from the end, a dubious situation is not going to be enough for an experienced referee to transform everything.