The Celtic midfielder was sent off in the first half of his side’s 4-1 loss to champions Rangers at Ibrox on Sunday.
His first booking was for a late tackle on Kent who had nutmegged him.
Warnock believes referee Nick Walsh could have taken the pace of the Rangers star into consideration.
"Not every foul is a yellow card,” he said on Sky Sports.
"It's a lovely piece of skill by Ryan Kent and sometimes the referee has to take that into consideration as well. He's done it well, and he's just caught him.
"I'm not so sure that's a yellow card, I'm really not. I think it's just the speed with which he moves into it.
"There's worst tackles that go on on football pitches than that to get a yellow card."
Former referee Dermot Gallagher had some sympathy for Celtic boss John Kennedy who thought the first yellow card was unfair.
"I think he thought it was just a foul,” he said. "Callum goes into this foul and he takes him with his back foot.
"In fairness to John I wonder if he's seen that from his vantage point. When you see it close-up it wasn't the tackle he made, it was the trailing foot that caught the player and the referee felt that was a yellow card.”
Gallagher compared the red card decision to one involving Newcastle United winger Allan Saint-Maximin and West Ham United defender Craig Dawson.
He said: "The referee has got to decide, has he broken up a promising attack? Well, obviously not, because they've not only carried on, but they've scored a goal.
"He then has to decide was it a reckless tackle? This goes back to a few weeks ago, Newcastle v West Ham, when Craig Dawson did a similar thing on the halfway line. He went into a tackle, Saint-Maximin got away, they ended up scoring a goal.
"Rangers have scored a goal so [the referee's] choice is, is it a reckless tackle? He's said yes, and it was a second yellow card, so unfortunately for Callum McGregor he had to be sent off.”