The only goal of the match came in the 83rd minute when Leandro Trossard found the net, securing a crucial win for Arsenal in their Premier League title push.
The result moved the London side five points clear of Manchester City as they continue their pursuit of a first English top-flight crown in 22 years.
The controversy erupted deep into stoppage time when West Ham believed they had levelled the score, only for the goal to be ruled out after a VAR review. Referee Chris Kavanagh was instructed by VAR official Darren England to check the incident at the pitch-side monitor.
The review focused on a challenge involving David Raya, with officials concluding that a foul had been committed in the build-up. After reviewing the footage, Kavanagh upheld the decision, disallowing the equaliser and confirming Arsenal's victory.
"Controversial. Due to, I think, the recent past of the Premier League, how it has been happening at corners, the blocks, and the holding," Espirito Santo told beIN Sports.
"So, I think everybody involved in football lost a little bit of perception what is or is not a foul - that's why we are upset. As in similar situations, there are different decisions.
"I don't quite understand. Sometimes it looks like a wrestling battle, so the concept of a foul is being driven away from what we used to see, and this leaves the players confused, leaving the crowd not understanding the reason behind the difference of decision."
