The presidential candidate and GOP frontrunner had said at CNN's Republican presidential town hall in Columbia, South Carolina that he "knew the real story" of the King of Pop.
Michael died at age 50 in 2009 from an overdose of the anesthetic propofol, administered by his private doctor, who served two years in jail for involuntary manslaughter.
Trump, 69, had said the singer was a "very good friend" who lived in his Trump Tower in New York City for a "long period of time", reported E! online.
"He had people that did numbers on him that were just unbelievable, facially, and, you know, the plastic surgeons," he added.
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Jeramine took to Twitter to slam Trump's comments, saying, "'Friends' don't pay tribute by peddling b.S. Theories about Michael's 'loss in confidence,'" Jermaine, 61, tweeted.
Trump has not responded to Jermaine.
The politician and real estate mogul, who is running for president for the first time, had also praised Michael in the past. In an essay he penned in Time magazine after the singer's death, Trump called him a "very good friend," a "genius" and "the greatest entertainer I've ever known.