Nottingham Forest had a first-half goal chalked off after Neco Williams was adjudged to have used his hand to force the ball over the goal line following a goalmouth scramble, while a separate penalty appeal for a foul on the same player also went unrewarded.
The result gave Tottenham their first point of the season and ended a four-game losing run against Forest, though Spurs failed to register a single shot on target from their 12 attempts at the City Ground.
"It feels we lost two points today because I watched a few situations back and I think the goal must stand. It's not clear and obvious," Glasner told BBC Match of the Day.
"We have a briefing before the season that the VAR threshold should be high again when VAR intervenes and I think it was not clear and obvious."
The Forest boss was equally frustrated by the penalty shout.
"For me it is a clear penalty when Neco Williams gets fouled because [Mohammed] Kudus doesn't even jump into the ball and when this situation happens anywhere on the pitch it is always a foul," he said. "In these two situations we were not very lucky. Huge fight from both teams and like last year every game is decided by small margins. I think we had them today on our side but if there is a disallowed goal in such a tight game we have to take the point."
Roberto De Zerbi, whose side remain winless in the Premier League since he took charge this summer, was more focused on his own team's failings in the final third.
"I think we played well but in the last third we have to improve. We have to take the better decisions. We have to keep more calm when we are very close to doing something important in the last third," the Tottenham head coach said.
Despite the lack of a shot on target, De Zerbi insisted his side had created enough to win the game.
"No, we could score three or four goals today. Because if you take the wrong decision, you don't score. But for me, it's a chance to score," he said.
He also pointed to the bigger picture given his short time in charge.
"We are not happy because we didn't win, but I think this is the right spirit and the right way to move on in this moment. Because we started just last Thursday to work all together and to create, to build the team, to build the organisation. It's not enough the paper, the transfer market."