U.S. President Donald Trump speaks in the Roosevelt Room of the White House in Washington, D.C., U.S., on Thursday, Aug. 23, 2018.

The op-ed, which was published online with the headline "I Am Part of the Resistance Inside the Trump Administration," details efforts by senior government employees who the author said were "working diligently from within to frustrate parts of his agenda and his worst inclinations."

"This is what I have to deal with," the president said, calling the op-ed "gutless" and a "disgrace."

"We have somebody in what I call the 'failing New York Times' that's talking about he's part of the resistance within the Trump administration," Trump told reporters during a meeting with sheriffs.

President Donald Trump launched a verbal attack Wednesday on The New York Times following its publication of an op-ed written by someone identified only as a senior administration official who claimed to be working with colleagues to thwart the president's agenda.

In response, the president touted his economic record, and said that when he leaves office "all of these phony media outlets will be out of business, folks. They'll be out of business because they'll be nothing to write and nothing of interest."

In a statement, the White House accused the author of the article of being a "coward" and called on him to resign.

"He is not putting country first, but putting himself and his ego ahead of the will of the American people. This coward should do the right thing and resign," the statement said.

Trump doubled down on his criticism of the op-ed in an evening Twitter post.

Donald Trump tweet: Does the so-called "Senior Administration Official" really exist, or is it just the Failing New York Times with another phony source? If the GUTLESS anonymous person does indeed exist, the Times must, for National Security purposes, turn him/her over to government at once!

The White House has been beset by leaks since its very first days, earning the fury of the president. Earlier this week, excerpts from a forthcoming book written by The Washington Post's Bob Woodward detailed internal conversations among senior White House officials including chief of staff John Kelly and Defense Secretary James Mattis.

Trump called the book a "con on the public." Both Kelly and Mattis said the book's reporting was false.

On Friday, off-the-record comments that Trump had made to Bloomberg concerning trade negotiations with Canada were leaked to the Toronto Star.

"Wow, I made OFF THE RECORD COMMENTS to Bloomberg concerning Canada, and this powerful understanding was BLATANTLY VIOLATED," Trump wrote in a post on Twitter at the time. "Oh well, just more dishonest reporting. I am used to it. At least Canada knows where I stand!"

Bloomberg denied leaking the president's comments.

— CNBC's Marty Steinberg contributed to this story.