Chelsea lost 1-0 to Tottenham in the first leg of their EFL Cup semi-final at Wembley.
Harry Kane scored the winning goal from the penalty spot in controversial circumstances.
The striker had been brought down by goalkeeper Kepa but referee Michael Olivier originally blew up for offside.
However, upon a VAR review the offside decision was overturned as a penalty awarded.
Sky Sports pundits Joe Cole and Robbie Keane both thought the decision was correct.
But Sarri claims fresh footage from a Chelsea camera viewed on his laptop shows Kane was in fact offside.
“A few minutes ago I watched the video from our camera. It was offside,” Kane said after the game.
“Our camera was in line with Harry Kane.
“Offside with the head, the knee. Offside.
“It was really important the linesman carried on running, he had a big impact on our defenders.”
Sarri then hit out at officials in the English game, claiming they don’t know how to use VAR properly.
“I don’t think English referees are able to use the system,” he said.
“If you are not sure with the system, you have to follow the ball and at the end of the action decide.
“But he stopped it and didn’t follow the ball – for our defenders it was offside. I don’t know about the goalkeeper but sure the defenders.
“I think they have to study the system.
“It’s very strange in the Premier League there isn’t VAR and in Carabao Cup there is the system.
“It’s very strange for us, the players and referees.”
Tottenham boss Mauricio Pochettino admitted he isn’t a fan of how VAR is implemented either.
Discussing the incident after the game, Pochettino said: “I don’t like the VAR. Today we get the benefit of it but after watching the World Cup and another league like La Liga I see that nobody is happy from day one that they started to use it.
“To get the benefit is nice but I am unhappy to win the game like this.
“I prefer the technology but in a different way. Being clear. I am pro technology because you cannot stop evolution but we are waiting so long, it is not clear what are the rules.
“We all have to agree, the players, the coaching staff, I watch every week La Liga and nobody is happy, the big clubs and the small clubs. If you are playing to win the title or to stay up nobody is happy.
“That is a good example for us. We have six months to improve the system and there is a lot of work to do.”