Trump, senior adviser to her father-in-law's reelection campaign, made the claim Monday on "Hannity," adding Republicans should just let the Democratic primary candidates attack each other.
"I think that we are seeing that the gloves are coming off on the Democrat side," Trump said. "And, this is why everyone is really excited to see what these Democratic debates hold for the Democrats, because who knows what they are going to say?
"They're going to start attacking each other. I have always said that we should just sit back and let them go at it."
Trump said the 2020 Democratic primary battle has been "interesting to watch," noting Biden was also mocked for a tweet he posted on Best Friends' Day.
The former Delaware senator posted a photo of a friendship bracelet that read "Joe" and "Barack."
"It is interesting that Joe Biden would tweet this, because didn't he say he didn't want Barack Obama's endorsement for his presidential run?" Trump asked.
Biden told Fox News in April he did not want Obama to endorse.
“Whoever wins this nomination should win it on their own merits,” he said outside a Delaware Amtrak station.
Trump's comments echo remarks conservative radio host Rush Limbaugh made earlier Monday.
The Florida-based commentator told a caller the photo was "pathetic."
"It’s not even desperation. It’s pathetic... he desperately wants Obama’s endorsement, and Obama laughed. So Biden’s trying to make it look like Obama’s his friend, he’s my friend, I like Joe, Joe likes me, I like Barack, and Barack likes me," Limbaugh claimed.