The Trump tweets come after the top lawyer for his transition team warned organization officials to preserve all records and other materials related to the Russian Federation probe. The official demanded anonymity because the official was not authorized to be named discussing the deliberations.
The obstruction of justice investigation into Mr Trump began days after Mr Comey was sacked on May 9, according to people familiar with the matter, The Washington Post said.
His morning missive apparently referred to Rod Rosenstein, the deputy attorney general whose role leading the federal investigation has become increasingly complicated.
DONALD Trump has said it is "sad" that seven months of investigations and hearings into possible links between his campaign and Russian Federation have been fruitless.
On Wednesday, the Washington Post reported that Mueller was investigating if Trump obstructed justice when he fired Comey.
As the legal rope has tightened, Trump's allies have gone on the offensive, questioning Mueller's credibility and floating the idea he may be fired.
The first is into whether anyone on Trump's campaign or associated with it, with him or with any of his businesses, may have had any illegal dealings with Russian officials or others with ties to the Kremlin.
The president has denied that he has any nefarious ties to Russian Federation and has also disputed that he's attempted to block the investigation into his campaign's possible role in Russia's election-related hacking. The newspaper noted Mueller had requested interviews with CIA Director Dan Coats, National Security Agency chief Michael Rogers and Richard Ledgett, the former NSA deputy director.
Trump also lashed out at the media, on a day that aides hoped would be focused on his decision to undo some of Barack Obama's detente with Cuba.
Details from those memos have been made public in news media accounts, and Comey himself detailed his conversations with Trump at a Senate hearing last week. The transition, a nonprofit structurally separate from the Trump campaign, continues to operate with a small staff.
Trump was alluding to the former secretary of state's handling of her private email server, an issue that dogged the Democratic nominee's presidential campaign since before it officially began.
The memos direct former staffers to prevent the automatic deletion of any records and former Trump transition officials are asked to send in materials to the Trump transition team. During his testimony before Congress on June 8, Comey stated that he thinks Trump sacked him in order to disrupt the FBI's investigation, according to Reuters.
This is what he said in May. "Nice, ' Trump tweeted, later repeating his accusation that the probe is a 'witch hunt".
Yet Trump's angry tweets on Friday underscored the near-impossible challenge his advisers and legal team have in trying to get him to avoid weighing in on an active probe.