Legendary NBA coach Gregg Popovich launched a stunning takedown of American President Donald Trump as he said "they system has to change" in relation to the racial injustice and inequality that America is railing against.

Protests and riots have broken out across the country, sparked by the death of black man George Floyd in police custody, as citizens take to the streets demanding an end to the systemic racism that has festered in the US for centuries.

Yesterday, peaceful protesters near the White House were forcibly pushed back by police using smoke canisters and rubber bullets so Trump could get his photo taken in front of St John's Church while holding a bible.

He also vowed to bring in the US military if the anarchy continued.

San Antonio Spurs head coach Gregg Popovich. Photo / Photosport
San Antonio Spurs head coach Gregg Popovich. Photo / Photosport

As Trump comes under fire for his handling of the unprecedented unrest in his country, Popovich — who has coached the San Antonio Spurs since 1996 and is also the national coach for Team USA — delivered a blistering attack on the Commander in Chief.

"It's unbelievable. If Trump had a brain, even if it was 99 per cent cynical, he would come out and say something to unify people," Popovich told Dave Zirin of The Nation.

"But he doesn't care about bringing people together. Even now. That's how deranged he is. It's all about him. It's all about what benefits him personally. It's never about the greater good. And that's all he's ever been.

"It's so clear what needs to be done. We need a president to come out and say simply that black lives matter. Just say those three words. But he won't, and he can't. He can't because it's more important to him to mollify the small group of followers who validate his insanity.

"What we have is a fool in place of a president."

Popovich also called Trump a "coward", a "destroyer" and a "deranged idiot".

"I'm appalled that we have a leader who can't say, 'Black lives matter'," Popovich said.

The 71-year-old also despaired that "without leadership and an understanding of what the problem is, there will never be change".