CHICAGO — Mayor Rahm Emanuel has for months derided President Trump’s immigration policies and his threats to cut off federal grants for so-called sanctuary cities like Chicago. On Monday, Mr. Emanuel took the dispute to court, challenging the federal crackdown with a lawsuit.

“Chicago will not let our police officers become political pawns in a debate,” said Mr. Emanuel, a Democrat, whose city received $2.3 million in law enforcement grants last year from the program that is now at risk.

The city is asking a judge to toss out new Justice Department rules that would make Chicago ineligible to apply for such grants unless it agrees to allow federal immigration authorities full access to its police stations and to provide 48 hours’ notice before releasing people wanted by immigration agents.

Chicago is by no means the first municipality to defy the Trump administration’s hard line against sanctuary cities. San Francisco and Santa Clara County, Calif., won an injunction in April against a broader federal effort to deny federal funds to local governments that limit their cooperation with immigration authorities. Seattle and Richmond, Calif., among others, have also sued.

But the litigation comes at a complicated time for Chicago, which has struggled with a persistently high murder rate, strained relations between residents and the police, and frequent jabs from President Trump, who has threatened to “send in the Feds” if local officials cannot tamp down the bloodshed. The particular funding itself, too, is essential, Chicago officials say, since it is aimed at solving the city’s crime problem.

Asked about the city’s new lawsuit, a Justice Department spokesman noted Chicago’s murder rate.

“In 2016, more Chicagoans were murdered than in New York City and Los Angeles combined,” Devin O’Malley, the spokesman, said in an email. “So it’s especially tragic that the mayor is less concerned with that staggering figure than he is spending time and taxpayer money protecting criminal aliens and putting Chicago’s law enforcement at greater risk.”

The dispute over sanctuary cities, where the local authorities limit their cooperation with federal immigration officials, pits two visions of public safety against each other.

Mr. Trump and his attorney general, Jeff Sessions, have argued that sanctuary policies like Chicago’s endanger American citizens and police officers by allowing undocumented immigrants who commit crimes to stay in the country and evade justice.

“By forcing police to go into more dangerous situations to rearrest the same criminals, these policies endanger law enforcement officers more than anyone,” Mr. Sessions said last week.

But Mr. Emanuel and Chicago police leaders argue the opposite. They say Chicago police officers make no inquiries about immigration status because doing so might fracture residents’ trust of the police and discourage those here illegally from reporting crimes or cooperating as witnesses, making the streets more dangerous.

Mr. Emanuel said the Trump administration was asking Chicago “to choose between our core values as a welcoming city and our fundamental principles of community policing.”

“It is a false choice, and a wrong choice,” Mr. Emanuel said.

Eddie Johnson, Chicago’s police superintendent, said the city “will not compromise the rights, safety or break the sacred trust of the people that live in and visit Chicago” in order to be eligible for federal funding.

The grants at stake in Chicago, which the city has used in the past for stun guns, SWAT team equipment and police vehicles, make up a tiny fraction of the city budget. But one supporter of the lawsuit, Gilbert Villegas, an alderman who is chairman of the City Council’s Latino Caucus, said there was “potential for that issue to creep into other grants” if it went unchallenged.

“I think it is a smart lawsuit,” said Mr. Villegas, whose ward was the site of a shooting this year involving an Immigration and Customs Enforcement agent that raised tensions among residents. “I think it’s something that we as a city need to do.”

The lawsuit adds to an already complex relationship between Chicago and the Justice Department. Chicago officials are waiting to hear whether Mr. Sessions plans to enforce a department investigation of the Chicago police, completed in the final days of Barack Obama’s presidency, that found a pattern of discriminatory practices.

On Monday, city leaders said they hoped for a preliminary ruling on the lawsuit before Sept. 5, the deadline to apply for new funding from the Edward Byrne Memorial Justice Assistance Grant program, which the lawsuit said provided “crucial support” for the police department. Two law firms are representing the city free.