Trump trade advisor Peter Navarro told CNBC on Monday that House Democrats "declared war on this president" when they opened an impeachment inquiry.

But while defending President Donald Trump over the whistleblower complaint fallout, Navarro found himself on the defensive in a "Squawk Box" interview, refusing to answer many of the direct questions about whether the White House had ever considered restricting U.S. investments in China.

Navarro come out swinging during the interview, calling House impeachment efforts "a coup d'etat."

"I think it's war," Navarro added. "The Congress has declared war on this president, the electoral process and the American people."

The office of House Speaker Nancy Pelosi was not immediately available to respond to CNBC's request for comment on Navarro's remarks.

Last week, Pelosi announced that the Democratic-led House will start an impeachment inquiry into Trump over alleged abuses of power concerning the president's potential efforts to push Ukraine to investigate the son of Joe Biden, Democratic presidential front-runner and former vice president.

Navarro characterized recent reports that the U.S. was considering restrictions on Chinese companies as grossly inaccurate and "fake news."

"That story, which appeared in Bloomberg, I've read it far more carefully than it was written," Navarro told CNBC. "Over half of it was highly inaccurate or simply flat-out false."

Several news outlets, including CNBC, reported Friday that the White House was thinking about ways to cut off the flow of American dollars to China and Chinese companies. A Treasury official said over the weekend that "the administration is not contemplating" such a move at "this time."

"We have reported in the past that there are some things under consideration that the administration has been evaluating at different stages of development, some brought by Congress, some originating internally," Kayla Tausche, a Washington correspondent for CNBC, asked before being cut off by Navarro.

"How long is this going to go on, Kayla?" Navarro asked. "You brought me on as a guest here. That was a follow-up monologue there."

Navarro, director of the National Trade Council at the White House, said that any reports that are not on the record with a Trump administration official are not to be believed, and should be treated "as entertainment not information."

"Closing Bell" co-host Wilfred Frost, who was substituting on the morning show, asked Navarro if he had ever conducted not-for-attribution briefings with reporters. Navarro refused to answer. (In journalism, not for attribution means a reporter can use the information from a source as background. Off the record is when a source tells a reporter something that cannot be reported without further verification.)

"Whenever these stories come out in the press, they're designed to basically have the White House reveal whatever is going on there, and I'm not going to do that," Navarro added.

Then later in the interview, "Squawk Box" co-host Joe Kernen asked Navarro what he expects when high-level talks in Washington, aimed at ending the more than yearlong trade war between the U.S. and China, resume Oct. 10.

"We'll see what happens," said Navarro. He then responded to a comment made by Kernen about hearing that a "lot from President Trump." Navarro said, "You can't negotiate in public. You just can't do that."