BUENOS AIRES — Thousands of union members and activists took to the streets of Argentina’s capital Wednesday to protest a decree from President Milei that imposes sweeping deregulation and austerity measures meant to revive the country’s struggling economy.

Unions had asked a court for a prior injunction to block measures lifting some labor protections, but a judge rejected the appeal, noting the decree had not yet entered into effect. It does so on Friday.

Argentine labor activists question whether Mr. Milei, a self-described anarcho-capitalist who has long railed against the country’s “political caste,” can impose the measures by way of an emergency decree bypassing the legislature where his party has few seats.

“We do not question the president’s legitimacy … but we want a president who respects the division of powers, who understands that workers have the need to defend themselves individually and within the framework of justice when there is unconstitutionality,” said the general secretary of Argentina’s construction workers’ union, Gerardo Martínez.

The protest went off peacefully, except for a confrontation between a small group of protesters and police. Journalists were caught up in the scuffle as police broke up the group of protesters, and some were beaten by police.

“The country is not for sale!” some protesters chanted, apparently referring to proposals that would allow the privatization of state-run industries.

Since taking office on December 10 following a landslide election victory, Mr. Milei has devalued the country’s currency by 50 percent, cut transport and energy subsidies, said his government won’t renew contracts for more than 5,000 recently hired state employees, and proposed repealing or modifying about 300 laws.

He says he wants to transform Argentina’s economy and reduce the size of its state to address rising poverty and annual inflation expected to reach 200 percent by the end of the year.

The General Labor Confederation read a statement at the march on Wednesday saying Mr. Milei’s decree “introduces a ferocious, regressive labor reform whose only purpose is to hamstring union activity, punish workers and benefit business interests.”

Mr. Milei’s administration has quickly faced protest. The government had said it will allow demonstrations, but threatened to cut off public aid payments to anyone who blocks thoroughfares. Marchers were also forbidden to carry sticks, cover their faces or bring children to the protest.

Mr. Milei, a 53-year-old economist who rose to fame on television with profanity-laden tirades against the political establishment, became president with the support of Argentines disillusioned with the economic crisis.

In a press interview ahead of the protest, he accused those who oppose his reforms of “not being aware of the seriousness of the situation.”

His initiatives have the support of Argentina’s Business Association which called them a “historic opportunity” to fight the “excessive size of the state” and the negative consequences of decades of budget deficits.