Republican presidential candidate Donald Trump at the US Open quarterfinals match between Serena Williams Venus Williams. Al Bello/Getty Images Real-estate mogul Donald Trump made it clear in a Tuesday interview that he was no fan of the Black Lives Matter movement.

"I think they're trouble. I think they're looking for trouble," the Republican presidential candidate said during a Fox News interview with Bill O'Reilly.

The Black Lives Matter movement seeks to call attention to what it describes as systemic mistreatment of African-Americans by police officers.

Protests affiliated with Black Lives Matter built momentum after a series of high-profile incidents over the past year in which unarmed African-American men died during their encounters with law enforcement, including in Baltimore and Ferguson, Missouri.

Trump told O'Reilly he saw some interviews featuring Black Lives Matter members and decided they were up to no good.

"I looked at a couple of the people that were interviewed from the group," he said. "I saw them with hate coming down the street last week talking about cops and police, and what should be done to them. And that was not good. And I think it's a disgrace that they're getting away with it."

The Republican businessman later said he was incredulously "watching the head of Black Lives Matter being interviewed the other night," though it's not clear whom he was referring to, as the loosely defined group doesn't have a centralized structure or formal leader.

Trump also used his O'Reilly interview to jab at Democratic presidential candidates who have stumbled while addressing Black Lives Matter.

Sen. Bernie Sanders (I-Vermont) had a campaign event upstaged by its protesters, while former Secretary of State Hillary Clinton and former Gov. Martin O'Malley of Maryland were both criticized for saying "all lives matter," a phrase some people feel minimizes the Black Lives Matter message. (O'Malley subsequently apologized, causing Trump to label him a "disgusting, little, weak, pathetic baby" in an interview last month.)

"I think it's disgraceful the way they're being catered to by the Democrats," Trump told O'Reilly. "And it's going to end up kicking them you-know-where. I don't think it's going to end up good. The fact is all lives matter. That includes black and it includes white and it includes everybody else."

He added: "And we have people, Democrats, that are afraid to even say that. They're apologizing because they say 'white lives matter' and 'all lives matter.' These are people that are unfit to run for office in my opinion."

O'Reilly also played for Trump part of a recent interview in which former Secretary of State Colin Powell, a prominent African-American Republican leader and former military general, defended Black Lives Matter. But Trump dismissed Powell's comments.

"He's wrong," Trump said. "He's totally wrong. It's 'All Lives Matter,' and that should be the theme of this country, frankly, or one of the themes. So he's obviously catering to somebody. I don't know who he's catering to."

Watch Trump's interview on 'The O'Reilly Factor' below: