"You want to be a legitimate president, sir? Then act like one," says the veteran, who according to the ad's sponsor is a Marine who lost a leg while on patrol in Afghanistan.
It lasts just 30 seconds. But in that half minute, the ad lands a series of punches at sore spots of Trump's ego, all delivered by a weightlifting unidentified veteran.
"President Trump, I hear you watch the morning shows," the veteran says in a voiceover.
"Here's what I do every morning," the vet says, as he squats to begin lifting a barbell in his garage.
"You lost the popular vote. You're having trouble drawing a crowd. And your approval rating keeps sinking," the vet's voice says, as the camera pulls back to reveal that he is lifting the weight while using just a single leg.
"But kicking thousands of my fellow veterans off their health insurance by killing the Affordable Care Act, and banning Muslims, won't help," he says.
"That's not the America I sacrificed for," the vet says. "You want to be a legitimate president, sir? Then act like one."
The veteran receives health coverage through the Veterans Affairs Department because of his service-related injury, according to the group, which did not identify him in the ad because of concerns that his family would be targeted for harassment. Not all veterans qualify for such health coverage.
Peter Kauffmann, vice chairman of VoteVets and a Navy veteran, said the ad will be running elsewhere as the group seeks to keep pressure on Trump.
"Since the White House comment line is down, and Donald Trump hasn't set up that veterans hotline he promised, we're going to go where we know Donald Trump is listening — 'Morning Joe,' and the other shows that he obsesses over," Kauffmann said.
"He's going to hear the message of this ad again and again. We're officially putting Mr. Trump on notice."
Shortly after the ad aired, Trump posted his first message of the day on the social media site Twitter.
Trump's Justice Department is appealing a federal judge's stay of his travel ban.
The president is also pressing ahead with plans to repeal the Affordable Care Act, and replace it with new health-care legislation.
But in an interview that aired Sunday night on Fox News, Trump said that replacement for Obamacare might not be ready until either the end of 2017 or next year.
"You have to remember Obamacare doesn't work, so we are putting in a wonderful plan," Trump told Fox News' Bill O'Reilly.