LOS ANGELES—A former U.S. Army infantryman was arrested for allegedly plotting to bomb a white nationalist rally in Long Beach, Calif., as revenge for attacks against Muslims, federal authorities said.

Mark Steven Domingo, 26, faces federal terrorism charges after hatching a plan to set off the device at the rally this past weekend, according to a criminal complaint unsealed Monday. Mr. Domingo, a recent convert to Islam, expressed support for violent jihad and considered attacking Jews, churches, and police officers before...