Slaven Bilic accused Phil Jones of "making a meal" of the challenge that saw Sofiane Feghouli sent off, a decision he said killed West Ham's chances of beating Manchester United.
Feghouli, making his first Premier League start for the Hammers, was sent off after lunging into a 50-50 tackle with United defender Jones just 15 minutes into the contest at London Stadium.
Hammers boss Bilic was furious with referee Mike Dean's decision to send off Feghouli, though, and claimed that a foul had actually been committed by Jones.
"It was never a red card. It was a challenge from both of them. The foul is Phil Jones. He got the ball but went with the scissors," he told Sky Sports.
"Sofiane Feghouli's foot was not high in the air, it was not deliberate. It was the key decision and it killed us. It put the game in a different perspective and was totally unfair for us.
"Phil made a meal of it, but you cannot blame him. Maybe he made a meal because he is the one who went in dangerously and he is saving himself."
West Ham were further incensed when Ibrahimovic's goal was allowed to stand despite the Sweden striker having drifted offside.
He added: "It was a big offside for the second goal. When the players are sprinting it is hard for the referees. I am the first to say that.
"But the players were walking. They should spot this."
"Ten men against a team like this is very hard, but we had chances. We had to score the goal when we had the chance," he said.
"That would have lifted us. I am disappointed with the result and frustrated by how we lost it, but I am proud of my players."
