Twitter Inc said on Tuesday it had placed a warning notice on a tweet from U.S. President Donald Trump for violating its policy against abusive behavior.

"There will never be an "Autonomous Zone" in Washington, D.C., as long as I’m your President. If they try they will be met with serious force!" the U.S. president's tweet read.

In a tweet, the company said it had hidden Trump's tweet behind its "public interest" notice because there was a threat of harm against an identifiable group.

Anti-racism protesters on Monday declared a Black House Autonomous Zone – referencing a Seattle area known as the Capitol Hill Organized Protest (CHOP) zone or the Capitol Hill Autonomous Zone – near the White House in front of St. John's Church.