President Trump’s declaration on Saturday that he had authorized the use of federal forces to “protect war-ravaged” Portland, Ore., prompted bewilderment and frustration — and more than a little sarcasm — in the city this weekend.

The president’s plans drew condemnation from state and municipal elected officials and a request to residents to stay calm.

“Let’s not take the bait,” Gov. Tina Kotek said.

Civic leaders are anxious to avoid a repeat of the summer of 2020, when federal law enforcement agents were called in to Portland to quell racial justice protests that followed the murder of George Floyd in Minneapolis. The demonstrations in Portland each evening attracted tens of thousands of people, and were met by the authorities with tear gas, rubber bullets and other crowd disbursement weapons.

For several months this year, a small but persistent group of demonstrators has camped in front of an ICE facility in southwest Portland, about two miles from the heart of downtown. Some in the crowd of one or two dozen people there has skirmished with federal law enforcement. Protesters have tried to block federal vehicles from leaving the building, and black-clad agents in armored gear have pushed them back, sometimes with force.

Mr. Trump’s announcement on social media made reference to those protests and others at ICE buildings in other cities, and it was quickly echoed by administration officials online.

Lori Chavez-DeRemer, a former Oregon congresswoman who is now labor secretary, described Portland as a “crime-ridden war zone.”