Klopp, in his first season coaching in the Premier League, is known for his outbursts of emotion on the touchline, enthusiastically celebrating goals while also having a few words with the match officials – something opposite number Van Gaal said he also used to do.
"When I was younger I was like Klopp," the Reds manager said. "Now at 64 I can control my passion more.
"I don't think the referees in England are influenced by what the manager or the fans do. Every manager has his own identity, his own personality and also his own philosophy.
"When I started my career I did that [Klopp-like actions] also. But I don't think you can influence from the touchline."
The now stern and often emotionless Van Gaal reveals how one particular action in 1995, when he was still coach of Ajax Amsterdam, made him change his ways.
"I did a karate kick," he said, laughing. "It was the 1995 Champions League final, Ajax against AC Milan, and I did a flying kick.
"We won 1-0, but we should have had a penalty for a high tackle on [Jari] Litmanen.
"I was angry, so I did a karate kick on the touchline – about a foot away from the fourth official's face. I wanted to show him what had happened to Litmanen.
"It should have been a penalty, but the referee did not whistle for a penalty. And in that moment, I realised that a manager can never influence the referee by what he does on the touchline.
"I realised that you have to control your passion. I know a lot of fans like the manager to show he is angry and at Newcastle [United] the other night I was angry when Jesse Lingard missed a chance to score [in the 3-3 draw].
"I am a little bit older now. But I still see the referee from 1995. He is a UEFA controller of referees now – and he reminds me what happened that night."
Liverpool and Manchester United face off in their EPL showdown at 16:05 this afternoon.