'Kenedy was the designated penalty taker, ' Benitez explained afterwards.
But the dominant Bluebirds couldn't find a victor despite controlling the second half with the help of impressive debutant Harry Arter.
Newcastle were well below par, compared to their efforts against Tottenham the week before, while Kenedy was lucky to escape a red card after blatantly kicking out at his opposition.
On a match which saw both sides collect their first points of the season, Benitez added: "It was a very unusual game".
"Regarding the penalty, Morrison's hand is outside the box and his body is inside".
Joe Ralls did well to pick out the unmarked Zohore in the six-yard area, but the Dane wasted the chance as he steered his header well wide of the mark.
He added: "Last week we drew and today we lost, but we are playing the way we want and the team has a lot of things to improve".More news: Manchester City's Kevin De Bruyne facing three months on sidelines
Camarasa looked destined to tuck the ball home from close range when Jonjo Shelvey nicked the ball away at the last moment.
The ex-Arsenal man went flying in from behind on Josh Murphy, giving ref Pawson the ideal opportunity to prove that he hadn't forgotten his red card after all.
Cardiff pressed and pressed to get a goal but they just couldn't find one.
Etheridge has now saved penalties in his first two Premier League games, after also denying Bournemouth from the spot on the opening weekend.
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Both sides battled on as the clock began to tick down, and despite having a numerical disadvantage had two golden opportunities to leave The Valleys with all three points.
'It was a poor penalty, he's not happy he missed a good chance.