BUENOS AIRES — Argentina is so used to celebrating immigration as a cornerstone of society that a 19th-century saying — to govern is to populate — remains in use to this day.

But in an abrupt shift coinciding with the immigration restrictions put in place by the Trump administration, President Mauricio Macri has issued a decree curbing immigration to Argentina, with his government declaring that newcomers from poorer countries in Latin America bring crime.

The measures announced by Mr. Macri in recent days made it much easier to deport immigrants and restrict their entry, prompting irate comparisons to President Trump and igniting a fierce debate over immigration.

“A decree like this scares people,” said Arfang Diedhiou, 33, a Senegalese immigrant who runs his own clothing store here in the capital, Buenos Aires. “It came out just after what Trump did, a coincidence that seems very strange to me.”