Huddersfield took a first-minute lead through Zanka but had striker Steve Mounie shown a straight red card for a foul on Yves Bissouma just past the half-hour mark.
The Terriers then had penalty appeals waved away when Alex Pritchard went down under a Pascal Gross challenge and Shane Duffy headed Brighton level moments later.
Wagner was also unhappy with a Leon Balogun challenge on Erik Durm, when the Seagulls defender was shown a yellow card late on.
In his post-match press conference, Wagner was asked if decisions cost his side and he simply replied "Yes".
Wagner was then asked about Mounie's dismissal and said: "For me the red card wasn't a red card.
"For me it wasn't but then the challenge on Erik Durm is for sure a red.
"I have to have consistency in decisions and from my point of view this wasn't the case.
"And if you've seen the Pritchard incident, it was a clear penalty and a red card as well because it was a clear and obvious goal chance two yards from the goal.
"It's what we should discuss today. When these big referee decisions go against you, football is not fun and you have no chance. No football team in the world would have a chance to be successful."
Wagner praised his players and added: "I really like how my players fought and how they tried to keep their head high against all these decisions.
"This is for sure not easy but this will bring us even more together as a group to show everybody that it's important. You only want the feeling you get judged fair and this wasn't the case today. This is why we can't speak from our point of view.
"I would rather speak about anything else rather than these decisions because they influenced and disturbed the whole football match and it was no fun."
On referee Michael Oliver, Wagner said: "The best have days off. All of them are humans and I've said this before.
"I'm pretty sure he wanted to do his best performance today like managers, players but sometimes this isn't the case and for me it was totally obvious it was the case.
"I'm not in the mood to speak to the referee. Everybody has seen it, what should I say?"
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