Several hundred people came to Civic Center Park to protest after reports of conditions in children's facilities raised alarm.
Online reports that an ICE agent was seeking student information had people concerned Monday.
Some Berkeley officials want to cut cords with the technology and data behemoths that aid Immigrations and Customs Enforcement.
Berkeley protesters joined groups around the Bay Area and the U.S. demanding the reunification of families separated at the border.
"There are many opportunities that have opened up for me," said Daniel Maher, who lost his legal status when he was convicted of crimes in the 1990s.
The person arrested Friday in Berkeley by ICE investigators is a U.S. citizen, federal authorities said Wednesday as part of media campaign to address community concerns.
Berkeley City College students opened a resource center this month that will provide legal and academic counseling to undocumented students and community members.
ICE agents arrested one person in South Berkeley on Friday morning in connection with a criminal investigation, authorities report.
Being able to remain calm in a crisis helped the third-year political science major get through nearly three weeks of detention by ICE.
Federal immigration officials are planning a sweep in Northern California sanctuary cities like Berkeley.
Cal student Luis Mora was granted the minimum bail, allowing him to return to school while he awaits his deportation hearings.
Undocumented Cal junior Luis Mora was arrested by Border Patrol agents in San Diego County when he took a wrong turn into a checkpoint.