Liverpool fans booing the national anthem before the FA Cup final was "not something I enjoyed", says manager Jurgen Klopp.
Liverpool supporters booed 'Abide With Me' and 'God Save the Queen' before kick-off at Wembley on Saturday.
However, the German boss also said: "It's always best to ask the question - why does this happen? They wouldn't do it without a reason.
"Maybe I'm not here long enough to understand. I am sure it's historical."
UK Prime Minister Boris Johnson condemned the booing.
Asked whether he thought there was ever a reason to boo the national anthem, his official spokesman said: "No.
"Obviously the events over the weekend, it was a great shame that as we were marking 150 years of the FA Cup, an event that brings people together, that a small minority chose to act in that way."
Liverpool lifted the FA Cup for the eighth time when they beat Chelsea in a penalty shoot-out following a goalless 120 minutes.
"I know a few fans from different clubs see this slightly differently but the majority of our supporters are wonderful people, really smart," Klopp added.
"They go through lows, go through highs, suffer together. They wouldn't do it if there was not a reason."
Liverpool are chasing a historic quadruple having already secured the Carabao Cup and FA Cup.
The Reds have the Champions League final against Real Madrid to come and they continue their pursuit of Manchester City in the Premier League with a trip to Southampton on Tuesday.
Why do Liverpool fans boo the national anthem?
John Gibbons from Liverpool fan podcast The Anfield Wrap said he was "surprised" the booing became front page news.
"It happened at the Carabao Cup final a few months ago and it happened in 2012 [FA Cup final] when we played the same opposition," he told BBC Radio Merseyside.
"What I would say to anyone buying these headlines is maybe look into why Liverpool fans act this way, why they feel a disconnect from the country and disconnect from a royal family sat on gold thrones telling people they are going to have tough times ahead.
"It's something Liverpool fans feel strongly about. It's a city that wants to be vocal about how we think this country should be and how we should live in a fairer society."
Gibbons called on people who criticised the protest to "maybe come up to Liverpool and speak to people and visit the food banks and see how some people in this city are struggling".
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