0321 GMT March 25, 2019
Merseyside Police have charged two Italian men following an attack on Sean Cox, a father of three from Ireland, near Anfield stadium on Tuesday, Sky Sports reported.
"The game on Tuesday night showed the beauty of the game, during the game, and it showed its most ugly face before the game," Klopp said.
"When I first heard about it, I cannot describe my emotions in English, to be honest. That should never have happened. It should never have happened before, should never happen in the future.
"The solution for it, probably nobody has that. It's unbelievable that something like this can happen. All our thoughts and prayers are with Sean and his family at the moment."
Liverpool, Roma, UEFA and Italian authorities were in a closed meeting at the Viminal in Rome on Friday to discuss security for Wednesday' second leg. This building is the seat of the Prime Minister and the Ministry of Interior.
Klopp said he had never before experienced the football violence which occurred outside Anfield this week.
"My whole life, I never thought it's nice they have a fight next to the stadium," the German coach added.
"But I really ask for responsibility from everybody. It's a football game, not more, not less. If Roma win the game and go to the final, they will deserve it. If we do, we will."
Asked for a message to Liverpool fans travelling to Rome, Klopp said, "Behave."