Multiple videos show the protester, 26-year-old Rakeem Jones, raising a middle finger to the crowd as security escorted him from the rally - before the unnamed supporter punched him to the ground.
INSIDE EDITION tracked down the supporter, 78-year-old John McGraw, who was unrepentant.
When asked if he liked the rally, he said: "You bet I liked it. Knocking the hell out of that big mouth."
And when asked why he punched the protester, he said: "Number one, we don't know if he's ISIS. We don't know who he is, but we know he's not acting like an American, cussing me... If he wants it laid out, I laid it out."
He added: "Yes, he deserved it. The next time we see him, we might have to kill him. We don't know who he is. He might be with a terrorist organization."
On Thursday, officials arrested and charged McGraw with assault and battery and disorderly conduct, according to the Cumberland County Sheriff's Office.
Jones told INSIDE EDITION on Thursday morning that his left eye still hurts from the punch and he remains confused about why he was being taken out by security in the first place.
He added that he doesn't regret going to the rally for the GOP frontrunner.
"Donald Trump probably doesn't care about what happened. He is already onto the next thing," he said. "If I can go to another [Trump] rally, I would go if I can."
When IE told Jones about his alleged attacker's comments, he said he did not have a response.
Jones attended the rally with friends.
"The people that are going to his rallies are hateful people," Jones' friend Ronnie Rouse told IE. "Not in general, because you cannot put a label on all of the people – but there is hatred."