The Belgian defender was shown a straight red for a two-footed tackle against Nani in City's 3-2 defeat, triggering a four-game ban at a crucial juncture of the season because he had been sent off previously.
Kompany, whose appeal against the card failed this week, said the decision by referee Chris Foy to dismiss him despite barely making contact with Nani, could set a precedent leading to many more similar tackles being punished.
"I wonder if we are now going to see an unprecedented wave of red cards because we sanction 'ifs' and 'maybes'?" the 25-year-old said on his Facebook page.
"Are we going to look back at video evidence for every single challenge that goes unnoticed by the officials, look at different scenarios and potential outcomes of what could have been considered a good tackle and then sanction it?
"Players and managers are starting to expect more sendings-off from referees and I think it's for the wrong reasons.
"I appealed because I obviously completely disagreed with the interpretation of the officials on the day but that happens in football and we move on."
City manager Roberto Mancini, who expressed his amazement at Kompany's sending off, was further bemused on Wednesday when Liverpool's Glen Johnson escaped punishment for a two-footed tackle during City's 1-0 League Cup semi-final defeat.
"There was a tackle from Glen Johnson that was worse than Vincent Kompany's against Manchester United," Mancini said.
Kompany, who missed City's defeat by Liverpool, will also miss the away leg and the home Premier League clash against title rivals Tottenham Hotspur.
