Twitter has for the fifth time placed a label over one of Donald Trump's tweets for violating its policies after he threatened "serious force" against protesters, escalating the microblogging platform's spat with the US President.

The tweet says: There will never be an Autonomous Zone' in Washington, DC, as long as I'm your President. If they try they will be met with serious force!

Trump's tweet referred to the police-free district created by protesters in Seattle, in Washington state, two weeks ago.

The zone was established in response to the killing of George Floyd, a 46-year-old African-American man who died during an arrest after a Minneapolis Police Department officer knelt on his neck for nearly nine minutes as three other officers looked on.

This is the fifth tweet from the president that the social media company has labelled in the past several weeks, The Washington Post reported on Tuesday.

Twitter said the tweet violates its policy prohibiting abusive behaviour and specifically the presence of a threat of harm against an identifiable group.

"We've placed a public interest notice on this Tweet for violating our policy against abusive behaviour, specifically, the presence of a threat of harm against an identifiable group," it said.

The warning label hides the president's tweet, and users have to click in to view the text.

Twitter has faced off with Trump over his account in the past few weeks, drawing his ire as the company labelled two of his tweets for misleading information about mail-in ballots, one for a manipulated video and one for inciting violence.

In response, Trump accused Twitter of working to stifle conservative voices and harm his re-election campaign.

Last month, he signed an executive order intended to roll back legal protections for Twitter and other internet companies. A lawsuit has been filed to block the order.

Trump's tweet came after a group of protesters on Monday unsuccessfully attempted to pull down a statute of former President Andrew Jackson near the White House.

The protesters later tried to claim an area near Black Lives Matter Plaza as a Black House Autonomous Zone before police removed them, The Washington Post reported.