The author, claiming to be part of the "resistance" to Trump "working diligently from within" his administration, said: "Many Trump appointees have vowed to do what we can to preserve our democratic institutions while thwarting Mr. Trump's more misguided impulses until he is out of office".
Trump has accused the New York Times of committing "treason" after the paper published the article on Wednesday, which claimed that a coalition was at work within the administration to thwart Trump's "worst inclinations".
The Times reported that several White House officials still eyed Pence's staff as the source of the op-ed.
Trump supporters have been calling the New York Times en masse.
Trump's call is the latest test of the department's independence.
On the defensive over damning accounts of the inner workings of his administration, Donald Trump set out on Friday (Sep 7) to discredit the testimony that cast doubt on his ability to lead the United States.
Xi announces $60bn financing for Africa
Xi said 50 China-Africa security assistance programmes will be launched under the flagship Belt and Road Initiative (BRI). Dozens of African leaders met with Xi ahead of the conference.
The president also told reporters he's "looking at" whether there are any actions that can be taken against the Times, which said it was taking an extraordinary step in allowing the piece to be published anonymously.
Trump described the White House as a "well-oiled machine".
That a covert network of officials was operating within the government to derail Trump's agenda became clear in the first months of the presidency.
Dao said he couldn't imagine any circumstances in which The Times' opinion section would identify the author.
So far, nearly all of the administration's top officials have issued statements denying writing the op-ed, from Vice President Mike Pence to the ambassador to Russian Federation. "And I ought to tell you, just I find - I find the media's efforts in this regard to undermine this administration incredibly disturbing", Pompeo said. "We did not", he said in a statement. I think their reporters should go and investigate who it is.
The Department of Justice said in response: "The department does not confirm, deny or otherwise acknowledge the existence or non-existence of investigations".
They lined up to deny writing an incendiary New York Times opinion piece that was purportedly submitted by a member of an administration "resistance" movement straining to thwart Trump's most unsafe impulses.