A US judge has ordered the Trump administration to restore the Associated Press's access to presidential events after the White House blocked the agency in a dispute over the term "Gulf of America".

District Judge Trevor McFadden on Tuesday said the administration's restrictions on AP journalists is "contrary to the First Amendment" of the US Constitution that guarantees freedom of speech.

The news agency refused to change its style from the Gulf of Mexico to the "Gulf of America" in its coverage, after President Donald Trump renamed it with an executive order.

The ban has meant that the AP has been unable to access press events at the White House as well as Air Force One.

Judge McFadden, who was appointed by Trump during his first term, said his ruling will not go into effect until Sunday to give government lawyers time to appeal.

"The Court simply holds that under the First Amendment, if the Government opens its doors to some journalists — be it to the Oval Office, the East Room, or elsewhere — it cannot then shut those doors to other journalists because of their viewpoints," Judge McFadden wrote in his ruling. "The Constitution requires no less."

The wire service had asked the court to rule that Trump had violated AP's constitutional right to free speech by taking the action because he disagreed with the words that its journalists use.

In February, Judge McFadden declined to immediately restore its access to presidential events.

After Tuesday's ruling, AP spokesperson Lauren Easton said the agency was "gratified by the court's decision".

"Today's ruling affirms the fundamental right of the press and public to speak freely without government retaliation. This is a freedom guaranteed for all Americans in the U.S. Constitution," she said in a statement.

The news organisation sued three senior aides to the Trump administration in February, saying the restrictions were unlawful and infringed upon press freedom.

The lawsuit specifically named Press Secretary Karoline Leavitt, chief of staff Susie Wiles and deputy chief of staff Taylor Budowich.

Lawyers for the Trump administration have argued that the Associated Press does not have a right to "special access" to the president.

Soon after taking office in January, the Trump administration signed an executive order renaming the Gulf of Mexico to the "Gulf of America", a move the White House said reflects the gulf's status as "an indelible part of America".

The AP said it would continue to use the term Gulf of Mexico, while acknowledging the Trump administration's efforts to rename it.

In response, the administration began clamping down on the AP's access to White House events covered by the "pool" of journalists that cover smaller events and report back to other media outlets.