The Citizens' 12-game winning streak came to an end on Wednesday night as they were forced to settle for a point at the Amex Stadium.
The Premier League champions thought they had scored a late winner when Erling Haaland headed home Cole Palmer's cross in the 79th minute.
However, the goal was chalked off by referee Simon Hooper following VAR intervention as replays showed the Norwegian striker tugging on Levi Colwill's shirt.
It was a similar incident in the first half when Bernardo Silva had his shirt pulled, but the visitors weren't awarded a penalty.
And it seemed as though Guardiola - and his assistant Rodolfo Borell - were making that point on touchline, with the City boss then manhandling linesman Adrian Holmes.
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He apologised shortly after having realised his mistake, but he was still shown a yellow card. Fulham striker Aleksandar Mitrovic was sent off against in March for something similar.
Describing the events on talkSPORT commentary as it happened, Sam Matterface said: "There's a bit of a bad reaction down on the touchline.
"Pep Guardiola has had to push his assistant Rodolfo Borell back towards the first row of the seating, he's not happy at all.
"Pep's moaning to the assistant of Brighton and Hove Albion."
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In reference to the Silva incident in the first half, Matterface remarked: "If you give one, you've got to give the other.
"And the VAR I think is a victim here of him [Hooper] being inconsistent, he should have called the foul in the first half, he didn't.
"And then we saw a similar one in the second. You might argue the first one wasn't clear and obvious, but it was clearly."
England legend Stuart Pearce then remarked: "I tell you what, Pep's just got hold of the linesman there and threw him out of the way."
Matterface then stated: "There was a bit of a contretemps down on this touchline.
"They are getting very heated this Manchester City bench, and he's got a yellow card Pep Guardiola for his actions, and he's still mouthing off at Simon Hooper.
"It's not worth it, you've won the title, leave it! I know he's a very competitive guy, but there will be Manchester United and Arsenal fans going now, 'dock them points for their behaviour.'
"That's not going to happen I'm afraid, but he's just slightly irritated I think by the disallowing of that goal and there's still a bit of anger emanating from the touchline."
Pointing out Guardiola then said sorry, Pearce announced: "I think Pep has just gone over there to make one or two apologies, I think he realised he overstepped the mark slightly.
"I think wrestling of the linesperson is frowned upon in these parts."
Having the final say, Matterface then quipped: "That assistant looks quite handy as well doesn't he? He's got incredible back muscles."
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Guardiola was asked about his yellow card in his interview with Sky Sports, where he said: "I was complaining about the goal being disallowed."
Commenting on Haaland's disallowed goal, he stated: "Watch it. Watch it, if it's a fault, every action for Erling is a fault."