Trump says feds won't respond to anti-ICE protests in Democrat-led cities

Massive rallies against immigration crackdown are ramping up across the United States from Minnesota to California.

US President Donald Trump has ordered the Department of Homeland Security not to step in demonstrations held in Democrat-run cities unless local authorities ask for federal assistance.

A federal judge in Minnesota has also denied immediate emergency relief of Trump's immigration agent surge in the state, allowing the clampdown to continue.

Protestors riding bicycles and carrying signs were seen marching against officers of the Immigration and Customs Enforcement, or ICE, in the city of Minneapolis on Saturday.

The protests were organised in memory of Renee Good and Alex Pretti, both fatally shot by federal officers in January.

Also on Saturday, Donald Trump issued new directives on the unrest and instructed Homeland Security Secretary Kristi Noem to not intervene in protests occurring in cities led by Democrats unless help is formally sought.

He said: "We want, I want the... I mean, honestly, the crime ridden cities are all Democrat-run cities. And if they want help, they have to ask for it. Because if we go in, all they do is complain. But if they want help, they can ask for it and they're going to need help."

The president gave no further details on how the order would affect the immigration operations, and put the onus on state and municipal officials to help protect federal government property, adding he had directed ICE and Border Patrol to be very forceful in the protection.

U.S. District Judge Katherine Menendez has denied Minnesota's request for an emergency order to immediately halt the major crackdown operation "Metro Surge" in the state.

The operation initiated in December last year was described by authorities as the largest immigration enforcement operation ever carried out and involved 3,000 federal agents currently deployed to the Twin Cities region.

The judge said in her ruling that evidence showed federal immigration agents engaged in racial profiling and excessive use of force, but noted halting the entire operation would go beyond the existing legal precedent and seriously undermine the federal government.

Attorney General Pam Bondi hailed the decision as a legal victory.

Meanwhile, as part of the "no work, no school, no shopping" strikes that swept across the country, thousands gathered in front of the city hall in Los Angeles, California, on Friday and marched to the federal detention centre to oppose Trump's immigration policies.