In earlier tweets, the president also berated former FBI deputy director Andrew McCabe, who was fired by Attorney General Jeff Sessions on Friday just two days before he was due to retire, and former FBI director James Comey, whom Mr Trump sacked last year. The latter firing led to the Mueller investigation being set up.Mr Trump accused Mr Comey of lying under oath before Congress, and described the contemporaneous notes that Mr McCabe and Mr Comey took following discussions with him as "fake memos".
Mr McCabe has given memos about conversations he had with President Trump to the Mueller inquiry, US media say.
The memos could support claims that Mr Trump sought to obstruct justice.
The president's lawyer, John Dowd, issued a statement on Saturday saying it was time for the special counsel's investigation to end.
But Republican Senator Lindsey Graham said Mr Mueller should be allowed to proceed without interference, and that many Republicans shared his view.
He also warned Mr Trump against any attempt to dismiss Mr Mueller.
"If he tried to do that, that would be the beginning of the end of his presidency, because we're a rule of law nation," Mr Graham said.
Why was McCabe fired?
Mr McCabe had been under internal investigation by the FBI and had already stepped down from his deputy post in January pending the review.
He was sacked just two days short of his 50th birthday on Sunday, when he was expected to retire with a federal pension.
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