LOS ANGELES — The end of encampments at some American college campuses this spring was not the end of pro-Palestinian protests at Harvard and UCLA.

Hundreds who attended annual graduation Thursday at Harvard College, Harvard University’s undergraduate college, staged a walkout to decry its disqualification of 13 students involved in earlier protests.

At UCLA on Thursday, administrators and Los Angeles police faced the return of pro-Palestinian protesters to the heart of campus.

On…