President Trump fat-shamed a man attending his rally in New Hampshire, thinking he was a protester — but the retired US marshal is actually an ardent supporter who later said, “I love the guy.”

When the president was interrupted by protesters during his speech in Manchester on Thursday night, he looked out in the crowd and noticed the plus-size man pumping his fist.

“That guy’s got a serious weight problem. Go home! Start exercising! Get him out of here, please!” yelled Trump, whose last physical showed he had put on the pounds.

“Got a bigger problem than I do!” he added. “Got a bigger problem than all of us. Now he goes home and his mom says, ‘What the hell have you just done?'”

It turns out the man the president mistook for a protester was Frank Dawson, a Trump supporter who was wearing a “Trump 2020” shirt.

The former marshal, who was identified by Fox News, had apparently just grabbed a couple of banners from a few protesters and thrown them away before they were ejected to cheers, according to the Washington Post.

Trump later placed a call to Dawson from Air Force One on his flight back to New Jersey, where he is on a working vacation at his Bedminster golf club.

A senior administration official said the president could not reach Dawson but left him a voicemail.

Dawson told the Boston Globe that the message was “a personal call to me from the president of the United States” that should remain private — though he shared some of Trump’s remarks.

“He thanked me for helping him out last night,” said Dawson, a resident of Woburn, Massachusetts, who also is a US Navy veteran.

Dawson reveled in the “rousing round of applause from everybody there” after he ripped the signs away from the protesters.

“It was the right thing to do,” he told the Globe.

Dawson said he didn’t hear Trump’s put-down because he had “tunnel vision” while dealing with the protesters.

He added that “it wouldn’t really matter. He’s still my president. I love the guy. I love what he’s doing for this country. … If President Trump gets good press out of it, I love it.”