The Hammers were denied a late penalty against German side Freiburg in the Europa League clash on Thursday night.
West Ham conceded an 81st-minute goal when Edson Alvarez lost the ball and substitute Michael Gregoritsch tapped into an empty net.
Moyes’ men chased an equaliser and managed to have a breakthrough in stoppage time when the ball hit an opposing player’s arm in the Freiburg penalty box.
There were appeals and protests for a penalty when the ball hit Noah Weisshaupt’s arm inside the penalty box.
Referee Alejandro Hernandez took a minimum of four minutes for a potential penalty on a long Video Assistant Referee (VAR) check.
Despite a lengthy review on the pitchside monitor, the referee refused to change his decision and opted to not award a penalty.
West Ham players and manager David Moyes were baffled by the referee’s decision and felt the side were denied a late penalty.
“I believe it’s a penalty kick,” said West Ham boss David Moyes afterwards. “In Europe they nearly give all the handballs. I don’t believe it’s the right way to go about it but I think that’s the way Uefa work.
“I find it difficult to see why not. It was harsh on us.”
The Hammers were favourites in the tie having already beaten their Bundesliga counterparts twice in the group stage.
David Moyes’ men were guilty of making several errors during the game and have only to blame themselves if they exit from the Europa League next midweek.
Jarred Bowen is the top scorer for West Ham this season with 17 goals but none in Europe, even though he had the chance to break the duck last night against the Bundesliga side.
West Ham will get the chance to overturn a 1-0 deficit in the return fixture in London Stadium next Thursday night if they want to progress to the last eight of the competition.