"Many of the thugs that attacked the peaceful Trump supporters in San Jose were illegals. They burned the American flag and laughed at police," Trump tweeted Saturday morning.
Several of the demonstrators could be seen waving Mexican flags, but Trump offered no evidence that undocumented immigrants were involved in the unrest, which was at times marked by physical altercations between his supporters and opponents.
Trump on Saturday also blamed San Jose Mayor Sam Liccardo for a lack of security during the protests.
"The Mayor of San Jose did a terrible job of ordering the protection of innocent people. The thugs were lucky supporters remained peaceful!" Trump tweeted.
On Friday, Liccardo, a Democrat, said in a statement
that he condemned "all acts of violence committed against people who exercise their rights to free speech and assembly."
He added, "It is regrettable that this has become a pattern for cities hosting Mr. Trump across the nation."
A spokesman for Liccardo told CNN Saturday that the mayor had no further comment.
The violence in San Jose Thursday night was roundly condemned across the political spectrum.
"It is very important for us to remind ourselves of who we are and what is best about American democracy and not slip into some of the bad habits that currently manifest themselves in the other party," President Barack Obama said at a private Democratic National Committee event in Miami
"We saw in San Jose these protesters starting to pelt stuff on Trump supporters," Obama said, according to a White House transcript of the event. "That's not what our democracy is about. That's not what you do. There's no room for violence."
Hillary Clinton and Bernie Sanders, the two Democratic presidential hopefuls, also condemned violence on the part of protesters as well. But Clinton told CNN's Jake Tapper that Trump has "lowered the bar"
for civility in using aggressive rhetoric at his rallies.
"He created an environment in which it seemed to be acceptable for someone running for president to be inciting violence, to be encouraging his supporters, now we're seeing people who are against him responding in kind," Clinton said.