"In the campaign, it was different because there was so much hate for Obama and Hillary Clinton," Cuban said in a "Squawk Box" interview. But now that Trump is in the Oval Office, the billionaire Dallas Mavericks owner said, "He's my guy now. This is my country."
An outspoken Trump critic, Cuban said he likes Trump's tax plan. "I [also] like a lot of the economic steps he's taking."
Cuban, an investor on "Shark Tank," said he likes some of Trump's Cabinet picks, but did not provide any names.
"I've had conversations with different people around [Trump]," he said. "I've tried to influence him with my thought process. And tried to learn about theirs."
It's a "good thing" that Trump is not a politician, Cuban said, but urged the president to do a better job communicating.
"I don't think he's done anything as a leader yet at all. Right now, he's a deal-maker," Cuban argued. "It's not about picking on Donald Trump. It's about doing what I think is right."
— Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank," which features Mark Cuban as a judge.