Mueller has signaled a willingness to accept written answers on matters related to collusion with Russian Federation.
Trump stressed Friday that he answered the questions personally, not his lawyers. Mr Trump's lawyer Rudy Giuliani has said repeatedly the president would not answer Mr Mueller's questions on possible obstruction of justice.
Trump added that he "just finished" the questions but has yet to submit them to the special counsel.
President Donald Trump told reporters on Friday that he has answered questions in writing that were submitted by special counsel Robert Mueller's team, but he hasn't turned them over to Mueller's team yet.
However, local analysts said the delay in submitting suggests that the president is still consulting with his lawyers. That move gave Whitaker, a Trump loyalist who Democrats have called a "political lackey", oversight of the Mueller probe.
Trump ended months of speculation on whether he would respond to questions from the special counsel, who is investigating whether the president's 2016 election campaign colluded with Russians and if Trump illegally obstructed the probe.
"The inner workings of the Mueller investigation are a total mess", Trump said on Twitter.
The probe, which Trump has referred to as a "witch hunt", has charged four Americans once affiliated with Trump's campaign or administration, 13 Russian nationals, 12 Russian intelligence officers, three Russian companies, and two other people in its look at Russian involvement in the 2016 USA presidential campaign.
The president did not say Friday when he would turn his answers over to Mueller.
"The witch hunt should've never taken place".
"I'm not agitated", he said.
Tensions have risen over the probe since Trump last week ousted Jeff Sessions as US attorney general and named Matthew Whitaker as his replacement on an acting basis.
Lindsey Graham in a meeting that special counsel Robert Mueller's investigation will proceed, according to a person familiar with the meeting.
Russian Federation has also denied any interference.
Pressed on his tweet storm Thursday in which he accused Mueller's investigators without evidence of going "absolutely nuts", the president assured reporters that nothing of note triggered his tirade but that it was a "continuation" of the objections he's already raised with the probe. Mueller was appointed as Federal Bureau of Investigation director by former President George W. Bush and Obama later extended his original 10-year-term by two years until 2013.
Four people connected with Mr Trump's campaign and presidency - campaign chairman Paul Manafort, advisers Rick Gates and George Papadopoulos, as well as former national security adviser Michael Flynn - have been charged and further indictments could be issued. "They are screaming and shouting at people, horribly threatening them to come up with the answers they want".