President Donald Trump crosses the South Lawn upon arrival at the White House on July 8, 2018 in Washington, DC. The First Family spent the weekend at the Trump National Golf Club in Bedminster Township, New Jersey.

Special counsel Robert Mueller is investigating whether President Donald Trump's tweets about Attorney General Jeff Sessions and former FBI Director James Comey amount to obstruction of justice, The New York Times reported on Thursday, citing three people familiar with the matter.

Mueller is investigating whether the president intimidated witnesses or sought to end the investigation, according to the report. The interest in the president's posts on Twitter is part of a broader inquiry that includes misleading statements from the White House and the dangling of pardons to possible witnesses.

The investigators are interested in the president's tweets criticizing Comey, who the president fired in May 2017, as well as Sessions, whom the president has publicly blasted for recusing himself from overseeing the Russia probe.

A spokesperson for the special counsel declined a request for comment from CNBC. The White House did not respond immediately to a request for comment from CNBC.

The president's outside attorney, former New York mayor Rudy Giuliani, dismissed the special counsel's interest in Trump's posts.

"If you're going to obstruct justice, you do it quietly and secretly, not in public," Giuliani told the Times.

The president has repeatedly denied any wrongdoing, and his attorneys have argued that the president is permitted to fire any member of his administration.

The president's attorneys are locked in negotiations with the special counsel over the contours of a possible interview with the president.

Giuliani said this week that the president would agree to an interview as long as investigators limited their questions to whether the president colluded with the Russian government. Trump would not answer questions on obstruction of justice, Giuliani said, according to Bloomberg.

Read the full report from The New York Times.

