West Ham starlet Ravel Morrison's frustration boiled over following the Hammers' 1-0 Premier League defeat at Crystal Palace.
The midfielder was fortunate not to receive a red card for shoving Palace's Joel Ward in the face.
Referee Lee Mason showed Morrison a yellow card, which means he will be suspended for Saturday's trip to Liverpool, after which West Ham could be in the relegation zone.
"I've been told there was an incident but I wouldn't like to comment," said Hammers assistant Neil McDonald.
"I'm more annoyed that that's his fifth booking so that's a suspension.
"I think it's out of frustration that we didn't get anything out of the game."
West Ham boss Sam Allardyce was "livid" with his players and official Mason after Stewart Downing's perfectly legitimate equaliser was chalked off for an apparent foul in the area.
McDonald added: "Sam is still a bit livid after the performance, not just of our players, but the officials.
"We feel a bit hard done by with the goal that we scored that was given as a foul. That stopped us getting on the front foot and getting back into the game.
"We saw the replays and couldn't work out where the foul was. Decisions like that cost people points, we were on the front foot, we were attacking, we created a good chance and it's been chalked off.
"It's hard to take really. We felt it must have been for offside, but apparently not."
West Ham are now just three points ahead of Palace and are still yet to record successive Premier League victories since they were promoted last year.