The nasty looking clash occurred during a Copa Libertadores last 16 tie in July, when Rojo's Boca Juniors side were knocked out of the competition by rivals Atletico Mineiro.
Argentine outfit Boca were left outraged by refereeing decisions in both legs of the South American equivalent of Europe's Champions League, and let their frustrations boil over into post-game chaos.
Boca had goals ruled out by the referee in both legs of the tie, which finished 0-0 on aggregate before Brazilian side Mineiro won on penalties.
A series of disturbing videos showed the Boca team trying to storm the opposition dressing room at the Estadio Mineirao, which was reportedly where the match officials were hiding out.
Security videos showed a number of dangerous objects being thrown within the tunnel area, with a clip of Rojo lifting a fire extinguisher off the wall and preparing to throw it.
The defender also reportedly punched a security guard during the chaos.
Police intervened using tear gas, but plenty of damage had already been done, with Rojo now finding himself in big trouble.
A statement from the South American football federation, CONMEBOL said: "Suspend the Player Marcos Rojo for five matches.
"Likewise, the Player Marcos Rojo is imposed a fine of USD 25,000 (TWENTY-FIVE THOUSAND US DOLLARS).
"The amount of this fine will be automatically debited from the amount to be received by CLUB ATLÉTICO BOCA JUNIORS, in respect of television or sponsorship rights."
Rojo was signed by Man United from Sporting CP in 2014, and went on to spend six seasons at Old Trafford, notching 122 appearances.
The erratic 31-year-old managed to avoid ever seeing red whilst in the Premier League, but has already been sent off since returning to his native Argentina.
During the famous Superclasico between Boca and rivals River Plate, Rojo managed to pick up two yellow cards in the first 16 minutes, contributing to a 2-1 loss for his side.