"I think that's a tough one because he is so intertwined and his life has been basically his company ... so disconnecting from that is an unnatural act for him," Schwarzman, a billionaire, said.
While "it'll take a while to work this out," Schwarzman claimed the president-elect is "sensitive to the issue."
Earlier this week, Trump tweeted that he would be holding a news conference with his children in December "to discuss the fact that I will be leaving my great business in total." But he did not outline any specifics as to how that process would work.
Trump has generated concerns about the possible blurring of politics and business when he takes office in January. Some have argued that Trump could run afoul of a constitutional clause guarding against enrichment from foreign governments, but it is not entirely clear if that rule applies to the president.
Earlier on Friday, Trump announced that Blackstone co-founder, Chairman and CEO Schwarzman will chair his strategic and policy forum, which will feature the heads of some of the largest financial, industrial and media companies in the United States.
Schwarzman told CNBC that he selected the business leaders for the forum and that the president-elect "loved them all."
When asked if he had been offered a Cabinet position, Schwarzman said, "That's not a relevant discussion."
"This is something that worked for me because I can't do something full time, given all the different things I'm doing now both not for profit and for profit," Schwarzman said.
— CNBC's Jacob Pramuk and NBC News contributed to this report.