Alameda was closed south of the 101 Freeway and north of Temple Street.
"We want the immediate repealing of SB 1070, which is the law in Arizona that just passed that criminalizes undocumented immigrants, not only undocumented immigrants, but all people that are not white," said protestor Francisca Porchas.
Police call it a "sleeping dragon," a favored technique of protesters. They bind themselves together using cables, PVC pipes and other materials, all designed to make it difficult and time-consuming for authorities to disband.
"Exercises such as this do pose risks," said LAPD Assistant Chief Michel Moore. "The department will work remarkably to do what it can to minimize that risk. Make no mistake about it: When we start physically cutting with saws and so forth into these type of pipe assemblies and so forth, there's always a risk that something could go wrong and a person could be injured."
Dozens of helmeted officers surrounded the demonstrators before declaring an unlawful assembly and moving in. No injuries are reported.
The demonstrators oppose Arizona's new law as well as local police cooperation with federal immigration restrictions. They favor legalization of illegal immigrants now in the U.S.
"We don't want any more military on the border," said Pochas. "We don't want laws or any national legislation that will increase military on the border, making it more unsafe for people to cross, creating more deaths in the desert."
Police said all 14 protesters were arrested and face misdemeanor charges for unlawful gathering.
The Associated Press contributed to this story.