Julius Malema, the party’s charismatic but controversial leader, who was once a member of the governing African National Congress, said in a speech on Saturday, “We make no apology about what the fighters did today against that store called H&M” and said targeting the stores was “just the beginning.”

“Every shop that undermines black people must be attended to,” he added. “It must be shut down. It must be closed.”

Image The image was later removed from H&M’s website. Credit... H&M, via Associated Press

The protests in South Africa capped a week of rapidly escalating outrage.

H&M apologized for the image on Monday, and then again on Tuesday, saying it had removed the image and stopped selling the sweatshirt.

“We have got this wrong and we agree that, even if unintentional, passive or casual racism needs to be eradicated wherever it exists,” it said on its website.

Celebrities, including the pop artist The Weeknd and the rapper G-Eazy, said they would no longer work with the company. The model’s mother, Terry Mango, said in a Facebook post that the backlash was an “unnecessary issue,” adding that “this is one of hundreds of outfits my son has modeled.”

Mr. Malema said the image had to be taken seriously. “We cannot allow the humiliation of black people to continue,” he said. “No one should make jokes about the dignity of black people.”