Leeds won via a late penalty for a hand-ball against James Tarkowski and converted by Lukas Nmecha.
Afterwards, Moyes said: "Leeds were better than us on the night but in the second half we might've had a chance.
"The goal is completely wrong, really harsh and it's difficult to lose to that. I've been in and spoken to the referee. They seem to think he was leaning. You're allowed to lean in football. It took a deflection and I don't know, did Tarky have to get his arm chopped off? He leaned across.
"It has not been a good weekend. Tonight that was a poor decision. VAR had a chance to get it right and fair, but I feel it was not fair. The crowd probably were the ones that were a bit intimidating but I can't see them intimidating the VAR people. It was a very good crowd for Leeds United.
"We can't do anything about it but it was a poor decision. We've lost a couple of important players but I'm not using it as any excuse and other teams will have injuries, unfortunately we've picked up a couple. If anyone was about to score it was likely to be us."
On potential signings in the rest of the transfer window, Moyes added: "I'm confident we will get something."