Purple Hearts are awarded to service members who suffer wounds in combat.
"Something very nice just happened to me. A man came up to me and handed me his Purple Heart," Trump told supporters at a campaign event here. "I said to him, 'Is that like the real one or is that a copy?' And he said, 'That's my real Purple Heart. I have such confidence in you.'"
Trump received the veteran, identified by his campaign as retired Lt. Col. Louis Dorfman, on stage at the start of the rally to receive the decoration. The campaign didn't specify which branch Dorfman served in.
"I always wanted to get the Purple Heart. This was much easier," Trump said.
Trump then pocketed the decoration after the veteran left the stage.
The New York Times reported
Monday that Trump received multiple student deferments and a medical deferment for a bone spur during the Vietnam War, successfully avoiding getting drafted into service.
Trump told Gray Television in an interview after the rally that he "regretted not serving in many ways" when asked about his five deferments to avoid the military draft during the Vietnam War.
Trump added that he was "fortunate" not to have to serve in the Vietnam War, which Trump called "highly contested and unpopular."
Illinois Rep. Tammy Duckworth, a Democrat running for Senate and a Purple Heart recipient, later tweeted out a picture of herself in the hospital.
".@realdonaldtrump, this is how one usually looks when you are awarded the Purple Heart. Nothing easy about it," she said. Duckworth is a double-amputee as the result of combat wounds she suffered in the Iraq War.
'Unfit to serve'
Trump's comments also follow his criticism of the family of Humayun Khan, a Muslim US soldier who was killed in the Iraq War.
Khizir Khan, Humayun's father, declared at last week's Democratic National Convention that Trump had "sacrificed nothing," prompting the Republican nominee to claim he'd been "viciously attacked" and questioning why Khan's wife, Ghazala, didn't make her own remarks. Trump, citing his business record, also said he believes he has "made a lot of sacrifices."
Democratic presidential nominee Hillary Clinton quickly hit Trump over his Purple Heart remarks, tweeting, "This from a man who says he's 'sacrificed' for our country."
Also on Tuesday, President Barack Obama called Trump "unfit" for the presidency following the Republican nominee's criticism of the Khan family.
"The Republican nominee is unfit to serve as president," Obama said at a White House news conference with the Prime Minister of Singapore. "He keeps on proving it."
Obama himself described his feelings as unprecedented, recalling disagreements with previous GOP presidential nominees Sen. John McCain and Mitt Romney -- but never an outright sense they were unfit to serve.
"The notion that he would attack a Gold Star family that made such extraordinary sacrifices on behalf of our country, the fact that he doesn't appear to have basic knowledge of critical issues in Europe, the Middle East, in Asia, means that he's woefully unprepared to do this job," Obama said.
Nadia McCaffrey, mother of Sgt. Patrick McCaffrey, a US Army National Guard soldier who was killed in Iraq in 2004, told CNN's Ana Cabrera on "Legal View" that Trump's response to receiving the decoration did not recognize "how deep this gift really is."
"Well, people have the freedom of speech and the freedom of action, so whoever gave that Purple Heart to Mr. Trump is, you know, it's his decision not mine," said McCaffrey, one of the Gold Star families who signed an open letter demanding an apology from Trump on behalf of the Khans
. "To me, a Purple Heart is sacred for what it represents and should not be given to anyone who didn't deserve one."