Deputy Attorney General Rod Rosenstein appointed Mueller to lead the special counsel investigation back in May 2017.
Public research universities already have a constitutional obligation to protect free speech and Trump offered no further details.
Cohen alleged on Wednesday that Trump paid hush-money to a porn star prior to his election and overstated his net worth for loans, insurance and tax purposes.
President Donald Trump on Saturday attacked U.S. Special Counsel Robert Mueller ahead of his report on alleged Russian Federation collusion by the Trump campaign in 2016 and said his political opponents were "trying to take me out with bullshit".
The manuscript was titled "Trump Revolution: From the Tower to the White House, Understanding Donald J. Trump" - and according to the Daily Beast, it was aimed at offsetting books deeply critical of the president.
"Just for the media, I'm sure he's a lovely young man, just had a little temper tantrum", Trump said.
"All of the sudden they're trying to take you out with bullshit", Trump said, in reference to Mueller's probe. "Can you imagine if we left interest rates where they were?"
Trump says that the CPAC people are probably thinking they're getting a lot more than they bargained for today.
The president struck a sarcastic note when condemning the Green New Deal, a progressive Democratic policy agenda that would merge environmental measures with the cause of economic justice.
But in what could spell a major legal headache for Trump, House Democrats are investigating whether the president hid from government ethics officials hundreds of thousands of dollars he paid Cohen as part of a scheme to silence porn star Stormy Daniels about her allegations that she and Trump had an affair years before.
He said the order doesn't set a bad precedent for future administrations because Democrats are "going to do that anyway, folks".
"The Green New Deal, or whatever the hell they call it, I encourage it", Trump said with a note of sarcasm. "And we can name every one of them if we want", Trump said while touching on the topic of the construction of the U.S. -Mexico border wall to curb illegal immigration. The move appeared to be a response to complaints by some university critics that institutions of higher education stifle right-wing viewpoints.
It was his first public appearance since coming home empty-handed, and to brickbats from all sides, from a nuclear-disarmament summit with North Korea's reclusive leader Kim Jong Un.
Trump still painted the summit as "very productive".