President Donald Trump and Secretary of State Rex Tillerson during a working lunch with African leaders during the UN General Assembly in New York on September 20. REUTERS/Kevin Lamarque Vice President Mike Pence and other top US officials intervened to persuade Secretary of State Rex Tillerson not to resign during the summer as tensions rose between President Donald Trump and the nation's top diplomat, NBC News reported on Wednesday.

Pence met with Tillerson in July to try to ease growing discord over policy, NBC News reported, citing 12 current and former senior administration officials and other people close to Trump.

Their meeting came days after Tillerson, in a session with Trump's national security team and Cabinet officials at the Pentagon, openly criticized the president and called him a "moron," NBC News said, citing three officials familiar with the incident.

NBC News said Tillerson's "moron" comment followed a meeting on Afghanistan in which Trump compared "the decision-making process on troop levels to the renovation of a high-end New York restaurant." Also around this time, Trump made a politicized speech to the Boy Scouts of America, which Tillerson once led.

Representatives for the State Department and the White House did not immediately respond to requests for comment by Reuters on the NBC News report.

Tillerson, in late July, had weighed whether to return to Washington from a personal trip to Texas but was reassured after discussions with Gen. John Kelly, now Trump's chief of staff, and Defense Secretary James Mattis, the network reported, citing four people with direct knowledge of the exchanges.

Tillerson said publicly in late July that he was "not going anywhere."

The White House declined to comment to NBC News, and a State Department spokesman told the network that Tillerson did not consider quitting in July and did not call the president a moron.

"Wow, so many Fake News stories today. No matter what I do or say, they will not write or speak truth. The Fake News Media is out of control!" Trump tweeted Wednesday morning shortly after NBC published its report. It was not clear which stories Trump was disputing.

However, Trump tweeted later Wednesday that, "NBC news is #FakeNews and more dishonest than even CNN. They are a disgrace to good reporting. No wonder their news ratings are way down!"

Over the weekend, Tillerson said the US had direct channels of communication with North Korea to see whether it was interested in dialogue in hopes of reducing tensions. The next day on Twitter, Trump said Tillerson was "wasting his time."

Tillerson with Vice President Mike Pence, center, and Secretary of Defense James Mattis at the White House on June 30. REUTERS/Jim Bourg

After the NBC News report on Wednesday morning, foreign-policy experts came out to encourage Tillerson to resign.

"Rex Tillerson has been dealt a bad hand by the Potus & has played it badly. For both reasons he cannot be effective Sec State & should resign," Richard Haass, the president of the Council on Foreign Relations, tweeted.

Haass wrote that it would be hard for anyone to be successful as secretary of state given Trump's policies such as leaving the Trans-Pacific Partnership trade deal and the Paris climate accord as well as the lack of staffing and money given to the State Department and the role of White House staff members. Haass also cited Trump's tweeting habits as an impediment.

The Eurasia Group's president, Ian Bremmer, also tweeted that Tillerson should leave his position.

"I know Rex and he's extremely capable," Bremmer said. "But he's now in an impossible position & should step down."

Tillerson is not the only Cabinet official to have publicly diverged from the president on policy issues.

Mattis on Tuesday said the US should consider staying in the Iran nuclear deal unless Tehran was proved not to be abiding by the agreement.

Trump has called Iran's 2015 deal with six world powers an "embarrassment."

Mattis has played down any tensions between Trump and Tillerson, most recently over North Korea.

Trump's White House and State Department have also taken differing stances on other foreign-policy issues.

Earlier this year, Trump backed Gulf Arab leaders in their boycott of Qatar even as Tillerson and the Pentagon cautioned against the military, commercial, and humanitarian effects of the dispute.