Donald Trump has threatened to walk out of future press briefings if reporters do not act with “decorum.”

The US President said this after a Washington DC court ordered the White House to return CNN reporter Jim Acosta’s press pass after it was revoked by the US Secret Service.

Acosta’s press pass was taken after he clashed with the President during a news conference earlier this month.

Trump played down the ruling, saying it wasn’t “a big deal”.

But, he said, “people have to behave”, adding his personnel were “writing up rules and regulations” for the press to abide by, including sticking to the agreed number of questions.

“If they don’t listen to the rules and regulations, we’ll end up back in court and will win,” Trump said, adding, “But more importantly, we’ll just leave, and then you won’t be very happy.

“You can’t take three questions and four questions and just stand up and not sit down. Decorum. You have to practise decorum,” Trump said.

Speaking outside the court earlier, Acosta praised the decision and told reporters “let’s go back to work.”

The judge said the White House decision likely violated the journalist’s right to due process and freedom of speech.

The ruling forces the White House press office to temporarily return Acosta’s “hard pass”, the credential that allows reporters easy access to the White House and other presidential events.

Acosta’s lawyer called the ruling “a great day for the first amendment and journalism.”

Acosta was barred from entering the White House a day after he had a heated exchange with President Trump during a news conference on November 8.