The Dutchman spoke in the defence of the Australian who was stood aside by the FIA as F1 race director as part of a revised refereeing system to be used in the sport.
Going forward, the role will be covered by two people, with the support of veteran official Herbie Blash and a virtual race control room.
However, that sweeping reforms to support the race director have been made, and that Masi has been replaced, doesn't sit well with Verstappen.
“For me, it's very unfair what happened to Michael because he's really been thrown under the bus,” the Red Bull driver told the press on Thursday in Spain.
“People talk a lot about what was decided in Abu Dhabi but can you imagine a referee in whatever sport has the coach or equivalent screaming in his ear all the time?
“I think in the first place that F1 already allowed that team members could talk to him while making decisions is very wrong because it needs to be, well, needed to be Michael making the decisions on his own without having people screaming in his ear.
“The people who now did sack him allowed that in the first place, for me [that] is unacceptable.”
However, the Dutchman wasn't done there as he heaped further praise on Masi, revealing he's been in touch with the Aussie during the off-season.
“I feel really sorry for Michael because I think he was a very capable and good race director,” he said.
“I have nothing against the new race directors because I think they're also very capable and very good race directors, but personally for Michael, I felt really sad, and I sent him a text as well.
“It's very hard to take over from someone like him [Charlie Whiting],” he added.
“He had so much experience from the previous years, and also Charlie had help around him.
“Maybe Michael just needed a little bit more [support].
“Everyone needs experience. I came into the sport, my first year if I look back at it now, I was a complete rookie.
“Now I'm so much further than what I was back then and I think it would have been the same for Michael.
“So to immediately sack him, for me, is not the right decision but I wish him all the best whatever comes next and I hope it is better than being F1 race director.”
“Michael was trying to protect us all the time, which is what we ask for a race director,” Alonso said.
“The decisions sometimes he will be okay for some are not okay for some others because you will never feel fair on some of the decisions, as I say happened to me on track limits on Lap 1.
“There are things that they will never be okay for everybody but said that I think the new guys are hopefully making the best job they can and keep protecting us as far as directors and applying the rules which is the only thing that we ask for.”
“I have a lot of respect for Michael, for what he has done,” added Leclerc.
“I'm sure that he has tried his best to take the best decision in his opinion all the time.
“It's always tricky,” he added.
“As we've seen in the last race, it's not easy, you need to take the decision quickly.
“I wish him the best and then for the future, let's see.
“I'm pretty sure that for FIA had has more information than we do on all of this and they took, in their opinion, the best solution for Formula 1, which I hope will be the case.”
Masi, who has been offered an alternative role within the FIA, has remained publicly silent since Abu Dhabi.