Vanthoor was third when Engel in the leading Mercedes-AMG rear-ended the second-placed BMW M4.
The Belgian driver lost control and slammed into the Armco barrier, ending his race.
Engle rose to third with the move, leaving factory BMW driver Raffaele Marciello and Ferrari’s Antonio Fuoco to battle over the lead of the race.
In the dying laps of the race, Marciello and Fuoco missed the third turn, Lisboa, in extraordinary scenes and gifted Engel the win.
“It’s a disgusting race result I find. I don’t think I’m the only one who finds this,” said Vanthoor on his post-race podcast Over The Limit.
“I got overtaken by the Ferrari in the last corner and then on the next lap Maro Bengel [sic] was behind me.
“He basically just punted me off the track and made me DNF my race. At the end, there is not much more to say than that.”
Vanthoor took issue with Engel’s move and the penalty that came with it. The former Erebus Motorsport driver was delivered a five-second penalty for the clash that ended the Team WRT driver’s race.
With such a large advantage over the second place BMW of Augusto Farfus, it meant Engel was able to win by six seconds.
Vanthoor was frustrated with the decision to only penalise Engel five seconds for ending his race.
“I would take out everyone,” said Vanthoor.
“Next time, if there are 10 cars on the grid I will take out everyone, nobody is driving anymore, I get a one-minute penalty, and I still win the race, if that’s how they do the rules.
“He did come to speak to me, but the things he said for me are below the ground. This is just how he is, we know it.
“There is one thing indeed what he did wrong if he now accepts it or not. He pushed me off, ruined my race, which is on him, fully on him, but then what happens after that is not his decision. He can not choose what penalty he gets.
“This is wrong on the organisation side and the people in the rooms deciding, looking at videos and having a chat with each other which penalty they would give. Nothing to anyone, but it’s on their side or on that area where it went wrong, especially today.”
In his post-race press conference, Engel offered Vanthoor an apology.
“I want to say sorry to Dries, it’s unfortunate we came together. Definitely not on purpose,” said Engel.
“I went for a move. He tried to close and we came together slightly and I think he tagged the wall, so sorry to him for that.”
