John McGraw - who later said that next time "we might have to kill him" - was also charged with battery and disorderly conduct after the event Wednesday night in North Carolina, the Cumberland County sheriff's office told the local TV station WRAL yesterday.
The incident was condemned by Bernie Sanders, who is vying with Hillary Clinton for the Democratic nomination for the White House.
"No one in America should ever fear for their safety at a political rally. This ugly incident confirms that the politics of division has no place in our country. Trump should take responsibility for addressing his supporters' violent actions," Sanders said.
McGraw was not arrested until Thursday morning, as video of the assault gained widespread attention. He was released after posting a USD 2,500 bond, CNN reported.
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The Cumberland County sheriff's office did not immediately return phone calls from AFP.
Rakeem Jones, the man who was punched, told The Washington Post that the sharp blow to the right side of his face caught him by surprise.
Jones, 26, said he went to the Trump rally as a "social experiment."
A woman who was part of his group started to yell out against Trump when he began his speech, Jones said.
As he walked up the stairs, right before reaching McGraw's row, Jones is seen in the video turning to his right, smiling as he raises his arms and says something to the crowd. McGraw then sucker-punched him.
"We don't know who he is but we know he's not acting like an American," McGraw said.
"Yes, he deserved it. The next time we see him, we might have to kill him."
Trump's rallies tend to draw large crowds, and some have been interrupted by protesters critical of the Republican frontrunner's policy positions on immigration and other sensitive issues.
Critics say he is stirring hatred among angry American voters with his inflammatory comments against Muslims and Mexicans.