"There's nothing really Reaganesque" about Trump, Reagan told CNN's Michael Smerconish. "I mean, my father was humble. That's not what you find in a Donald Trump, I might say."
The comments follow Reagan's tweet earlier this week in which he said Trump is the first presumptive Republican nominee that his father would not have supported.
On the campaign trail, Trump often compares himself to President Reagan. But Michael Reagan, president of the Reagan Legacy Foundation, said the two men couldn't be more different.
"He wasn't demeaning. He didn't talk down to people. He talked with people, which is the complete opposite of what Donald Trump, in fact, does," he said.
Michael Reagan, a friend of former House Speaker Newt Gingrich, said it would be wise of Trump to select the former Georgia congressman as vice president.
"I think it would be a good choice. He needs somebody who certainly knows Washington. And certainly knows the Congress of the United States of America," Reagan said, adding that Gingrich might offer Republicans uneasy about Trump a palatable alternative.
"But what happens is people always vote for the top of the ticket," Reagan acknowledged. "They don't vote for second place."
Reagan said Gingrich needs to pull Trump aside and tell him to show more humility.
"Donald Trump would go a long way to apologize to the judge, apologizing to Ted Cruz's father, apologizing to Marco Rubio and apologizing to many other people. And humbling himself and going forward, if he doesn't do that, he's going to have a lot of trouble winning the election in November," he said.
Reagan has criticized Trump before. In September, he told Smerconish
that of all the 2016 candidates who were still in the race at that time, Trump was the candidate least like his father.