Massimiliano Allegri said the 40-year-old Buffon and been "a role model for over 20 years" after the goalkeeper saw red during a match against Champions League conquerors Real Madrid.
Buffon was sent off for dissent in the final minute of a 3-1 quarter-final defeat in Madrid on Wednesday after confronting English referee Michael Oliver over his decision to award the hosts a penalty in time added-on.
The Juventus captain has come under fire for a post-match rant in which he laid into Oliver.
But Allegri said Buffon's outburst was "understandable" after Oliver "slightly lost his way" in a tense finale that saw Madrid advance to the semi-finals 4-3 on aggregate.
"For over 20 years, Gianluigi Buffon has been a role model both on and off the pitch," Allegri said on Saturday.
"If on one occasion he said the things he did, in a situation as tough as Wednesday night's, that is understandable and I challenge anyone to react differently."
"The referee had a very good game for 90 minutes, he really did. He then slightly lost his way at the end, like when you pull up a Monopoly card with an unpredictable twist, but these things can happen.
"I don't know if it was correct or not, I don't care, but Buffon was also sent off and therefore denied the opportunity to save the Cristiano Ronaldo penalty. Gigi's reaction is to be understood."
Juventus play Sampdoria on Sunday as the Serie A champions bid for a seventh straight title with Napoli four points behind in second.