Boca were 3-0 ahead with only a few minutes to play when the 30-year-old infuriated the opposition by using the 'rabona', where the kicking foot is wrapped behind the standing leg, to cross the ball into the San Lorenzo area.
Seconds later Buffarini was pushed to the ground and surrounded by irate San Lorenzo players. Buffarini's team mates came to his defence, leading to a scuffle on the goal line.
The protests continued as Buffarini got to his feet and he was then shown a yellow card.
Buffarini, who spent four seasons at San Lorenzo, later apologised.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
"I got overconfident, I apologise one thousand times to the players of San Lorenzo and their fans," he said. "It wasn't the moment for a 'rabona', I realised that afterwards."
Boca won 3-0, a result which extended San Lorenzo's winless run to 15 matches in all competitions.
(Writing by Brian Homewood; Editing by Peter Rutherford)
