The incident was checked by VAR but referee Simon Hooper was not ordered to consult the monitor. O’Neil was then shown a yellow card by Hooper for his protests.
The Wolves head coach said former Premier League referee Moss, now the Select Group 1 Manager at PGMOL, admitted the incorrect decision was made.
“I was told live that they didn’t think it was a clear and obvious error but having just spoken to Jonathan Moss — and fair play to him for coming straight out — he apologised and said it was blatant penalty and should have been given,” O’Neil said.
“I sometimes feel bad because he’s come out and been honest.
“I spent a lot of time with him today. I gave up most of my afternoon trying to understand the new guidelines and trying not to get myself booked in the first game with the new guidelines, which I failed in.
“Fair play to Jonathan for coming out and saying it was clear and obvious error, he can’t believe the on-field referee didn’t give it and he can’t believe VAR didn’t intervene.”
Wolves were on the receiving end of a number of apologies from PGMOL chief refereeing officer Howard Webb last season and notably saw an FA Cup third round winner against Liverpool disallowed as VAR did not have the correct images to judge the angle of the offside.
O’Neil had told Sky Sports earlier:”I thought live that it was a penalty. I thought it looked like the goalkeeper almost took our centre forward’s head off… and when I watch it back it looks the same. Really, really surprised.
“I think it’s a foul. When you go for the ball and clatter into an attacking player that hard I think it has to be a foul. I’m not overly surprised we didn’t get it to be honest.
“As he (Hooper) jogged over towards us I thought he might be going to the screen but as it turned out he booked me and not Onana.”
On Hooper not being told to consult the monitor, O’Neil added: “I understand it (sticking with on-field decisions as much as possible) but I don’t accept it fully. I think the on-field referee, it’s a really difficult decision for them. So we can’t just leave it because they (VAR) have said no.
“If we all think it’s a penalty and a lot of people coming through already saying they think it’s a stonewall penalty so (I’m) disappointed but we shouldn’t be talking too much about that.”
Erik Ten Hag admitted the decision to not award a penalty could be debated but that ultimately the correct call was made.
“After the opponent touched the ball he dived in so it was the judgement of the officials and lucky for us no penalty,” the United manager told BBC Sport. “I think you can debate it but I think no penalty.”
United secured a 1-0 victory at Old Trafford thanks to Raphael Varane’s second-half header. The match was O’Neil’s first in charge of Wolves, having been appointed Julen Lopetegui’s successor just five days earlier.
United return to action on Saturday evening when they travel to Tottenham, while Wolves welcome Brighton to Molineux earlier in the day.
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(Photo: Simon Stacpoole/Offside via Getty Images)