Marcus Rashford's goal in Manchester United's 1-1 draw with Liverpool demonstrated "all the problems with VAR", said Jurgen Klopp.
The England striker put United ahead after 36 minutes of a tightly fought contest at Old Trafford, where Ole Gunnar Solskjaer's side brought Liverpool's 17-match Premier League winning streak to an end.
Liverpool appealed for the goal to be ruled out for what they claimed was a foul by Victor Lindelof on Divock Origi before Rashford broke the deadlock, and Klopp insisted after the game that his striker was taken down illegally.
Adam Lallana's 85th-minute equaliser rescued a point for the Premier League leaders, but the draw did not keep Klopp from questioning referee Martin Atkinson's decisions.
"[In the] second half we had good moments," Klopp told Sky Sports. "The first half I did not like.
"We gave United the opportunity to do what they wanted to do, being aggressive and challenges everywhere. It's football, but you have to pass these lines. The opportunities were there.
"They were better in the game than we were. They defended well but at the end United scored a goal which shows all the problems with VAR.
"Mr Atkinson lets the game run because I am sure he thinks VAR will show if there is contact. There is a foul, 100 per cent it is clear it is a foul.
"We cannot change it but in general there is a problem. They still have 60 or 70 yards to run until they scored a goal but still."
The result prevented Liverpool from restoring their eight-point lead over second-place Manchester City, but Klopp praised his side's strong finish to the game.
The Reds were on top in the closing stages and substitutes Alex Oxlade-Chamberlain, Naby Keita and Lallana earned special praise from their manager.
"The result is OK, it's not what we wanted before the game but the way it developed we have to be happy because United were for a long time 1-0 up," said Klopp.
"Pretty much everything went against us, but we did not lose. We deserved a point. In the last 15 minutes we were in charge of the game.
"They were purely there to defend against us. It's difficult. We should have done much better.
"When Ox came on it was good, Adam came on and helped us a lot, Naby maybe came on a bit late but had influence. Adam scored [and] that is a wonderful story to be honest."