Carvalhal who took over at the league's bottom club in December, was referring to a first-half incident when Mike van der Hoorn's header struck Newcastle defender Mohamed Diame's arm on the goal line with the score 0-0.
"I must be honest from the bench I didn't see in that moment," Carvalhal told the BBC.
"My assistant says that it's a very clear penalty and a red card also, so it's another decision that creates something important but what can we do?
"Nothing, only talk about this. This is one of the situations VAR will in the future say clear penalty – it will be clear."
Brighton and Hove Albion's third-round FA Cup tie against Crystal Palace on Monday was the first competitive club match in England in which the VAR was used, having first been deployed in the country for England's friendly with Germany last month.
Newcastle stretched their winless home run in the Premier League to seven games and continued to slide towards the relegation zone after missing an array of chances against Swansea, who took the lead against the run of play.
Poor finishing and several fine saves by Lukasz Fabianski kept the home side at bay before Jordan Ayew fired the visitors ahead on the hour, heading a Van der Hoorn cross past Karl Darlow after the home team's keeper parried his first attempt.
Substitute Joselu levelled eight minutes later not long after coming on, threading a sublime finish from a tight angle into the far corner through the legs of defender Alfie Mawson and past the wrong-footed Fabianski.
The result left the Magpies, who had made a bright start to the season, in 14th position on 23 points from as many games, only three more than 18th-placed Stoke City who have a game in hand as they visit Manchester United on Monday.
Newcastle boss Rafa Benitez rued his team's profligacy in front of goal.
"I think that it's more or less something we have seen in the past, we created enough chances to score in the first half and then we concede," he said.
"It's always difficult to be happy when you draw at home but the main thing is the reaction and how we were pushing at the end. We have to learn that every single mistake can cost you."
(Writing by Zoran Milosavljevic; Editing by Christian Radnedge)
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