"We had to obviously make a late change because of the private situation involving Luis Diaz," Klopp said ahead of Sunday's game at Anfield.
"It's a worrying situation for all of us and it was a pretty tough night.
Earlier, Liverpool issued a statement saying they were aware of the situation involving Diaz's family and were focusing on the player's welfare.
Diaz, who has played 43 times for Colombia, was signed by Liverpool in January last year in a deal reported to be worth 45 million euros ($47.5 million).
He has scored three times for Liverpool in all competitions this season.
Persons:
Liverpool's Luis Diaz, Everton's Michael Keane, Carl Recine, Luis Diaz, Juergen Klopp, Gustavo Petro, Klopp, Diaz, General Francisco Barbosa, Luis Diaz's, Barbosa, Rohith Nair, Luis Jaime Acosta, Hugh Lawson, Ken Ferris
Organizations:
Soccer Football, Premier League, Liverpool, Everton, Anfield, Everton's Michael Keane REUTERS, Sunday's Premier League, Nottingham Forest, Colombia's, Sunday, Thomson
Locations:
Liverpool, Britain, Colombia, Venezuela, he's, Bengaluru, Bogota