Billionaire investor Carl Icahn said he was surprised by parts of Donald Trump's inaugural address Friday, particularly the newly inaugurated Commander-in-Chief's broadside against the political establishment.

As a candidate, Trump ran against the established party grandees of both major parties, a challenge he stuck to in his first speech as president.

"Donald surprised me coming on so strongly about the establishment. I admire him for doing that," Icahn told CNBC on the sidelines of the inauguration parade.

"I admire him for not just trying to say, 'Wow. Let's smooth it over. Let's be buddies.' I mean, he came on extremely strongly and he's giving you a look at what the future, I think, is going to be," Icahn added.

Trump said this particular Inauguration Day was special because it marked the transfer of power, not just between parties, but from Washington, D.C. to the people.

"For too long, a small group in our nation's capital has reaped the rewards of government while the people have bore the cost. Washington flourished, but the people did not share in its wealth ... That all changes starting right here and right now, because this moment is your moment," Trump said in his inaugural address.

Trump's inauguration is a "major, major watermark" in U.S. history because it marks a "secular change in our government," Icahn argued.

Icahn, Trump's special advisor on regulatory reform, said he expects the 45th president of the United States to take a confrontational approach, to some extent. Yet he argued that may be a good thing because it will promote change.

"I think you have to break up this establishment. You have to stop the perception which we have in this country that the government is at war with business, that the government doesn't like business and that's what you've had for eight years with Obama," Icahn said.

The billionaire investor has been a vocal opponent of regulation, some of which he called "literally crazy" or "idiocy."

Icahn, a major fossil fuel investor, has frequently criticized Obama administration energy restrictions. He told CNBC in a recent interview that he supported Trump's choice of Oklahoma Attorney General Scott Pruitt, who has battled the Obama administration EPA and expressed doubts about how much humans affect climate change.

Icahn previously said the EPA was one of the worst-run agencies he had ever seen.

— CNBC's Jacob Pramuk contributed to this report.