Escalating its aggressive push for a quieter spring break, Miami Beach declared a three-night curfew beginning on Friday, citing the large crowds it expects over what has usually been the peak weekend of the season.

The curfew will run from midnight through 6 a.m. each night until Monday, Alina T. Hudak, the city manager, announced on Friday morning. It will apply only to South Beach, the part of the city most popular with tourists and revelers.

“We did not make this decision lightly, but it should not come as a surprise,” Ms. Hudak said in the announcement. “We have been very clear about our intent to protect the public from the dangerous mayhem that has accompanied spring break crowds in recent years.”

The sale of alcoholic beverages for “off-premises consumption” — read: on the street — will also be prohibited after 6 p.m. each day the curfew is in place.

How to get a handle on spring break has become a dominant question for Miami Beach leaders since rowdy crowds began flocking to the city every March after the start of the coronavirus pandemic. Some of the city’s tactics have drawn charges of overpolicing and racism, as well as lawsuits over civil rights violations. This is the fourth consecutive year in which Miami Beach set an emergency spring break curfew.

Mayor Steven Meiner and some commissioners — who were elected on a law-and-order platform in November — debuted a digital ad campaign last month saying that the city was “breaking up with spring break.” They instituted a slew of measures for last weekend and this weekend, traditionally the busiest ones of the season, that included using license plate readers, restricting beach access, closing public parking garages and prohibiting sidewalk cafes on popular Ocean Drive.