Outside the venue, campus police kept both sides separated.
Inside the event, Trump and his girlfriend, political analyst Kimberly Guilfoyle, got into a loud exchange with a handful of vocal protesters.
The event was organized by a group called Turning Point USA.
Trump and Guilfoyle were also scheduled to visit the Ronald Reagan Presidential Library for a lecture and book signing.
Trump's book, "Triggered: How the Left Thrives on Hate and Wants to Silence Us," was recently released.