The US judge in charge of the CNN allegation ordered the White House to reinstate the entry of CNN correspondent Jim Acosta to the US president's headquarters immediately.
Judge Timothy Kelly said journalist Acosta had suffered irreparable damage because the White House had withdrawn his statement.
The judge also rejected the White House's claim that CNN could replace another reporter with correspondent Acosta.
Trump's management earlier canceled Acosta's approval after entering into a heated debate with the president at a news conference following the results of the midterm elections.
After Acosta raised questions about immigrants and Russia's intervention in the 2016 election, Trump stopped the reporter, describing him as a rude and horrible person. "You do not have to work for CNN," he said.
CNN has filed a lawsuit against the White House for violating the first constitutional amendment to protect freedom of the press and the profession. It also demanded that journalists be allowed to enter the White House and protect their right to access information.