DUBAI, United Arab Emirates  — Iran’s president on Thursday accused America of conducting a “failed policy of destabilization” targeting his nation, as Iranian protesters call for regime change despite a violent and wide-ranging crackdown, including almost 100 killed at the eastern city of Zahedan by security forces.

President Ebrahim Raisi has repeatedly dismissed the unrest sparked by the death of a 22-year-old woman in policy custody as a purported Western plot, without providing evidence. His latest remarks came after protests erupted in cities across Iran on Wednesday, with videos showing security forces apparently firing toward demonstrators.

The protests, in which girls and women of all ages have removed their mandatory headscarves, or hijabs, have become one of the greatest challenges to Iran’s theocracy since the country’s 2009 Green Movement. Mr. Raisi, a hard-line protégé of the Supreme Leader, Ayatollah Ali Khamenei, has likened the protesters to “flies” and sought to downplay the unrest.

“The Iranian nation has invalidated the American military option and, as they themselves have admitted, brought the policy of sanctions and maximum pressure a humiliating failure,” Mr. Raisi said Thursday at Astana, Kazakhstan.

“Now, following America’s failure in militarization and sanctions, Washington and its allies have resorted to the failed policy of destabilization,” he said, according to a transcript of his remarks.

Mr. Raisi did not otherwise address the demonstrations, which took place across at least 19 cities on Wednesday.

Gathering information about the demonstrations remains difficult amid the internet restrictions and the arrests of at least 40 journalists in the country, according to the Committee to Protect Journalists.

Iran’s government insists 22-year-old Mahsa Amini was not mistreated, but her family says her body showed bruises and other signs of beating after she was detained for violating the Islamic Republic’s strict dress code.

It remains unclear how many people have been killed or arrested so far in the protests.

An Oslo-based group, Iran Human Rights, estimated Wednesday that at least 201 people have been killed. This includes an estimated 90 people killed by security forces in the eastern Iranian city of Zahedan amid demonstrations against a police officer accused of rape in a separate case.

Iranian authorities have described the Zahedan violence as involving unnamed separatists, without providing details or evidence.

At Washington, a State Department spokesman, Ned Price, said America wasn’t focusing on possible negotiations with Iran over its tattered nuclear deal amid the demonstrations. Those talks collapsed in the months before Amini’s September 16 death.

“Right now our focus … is on the remarkable bravery and courage that the Iranian people are exhibiting through their peaceful demonstrations,” Mr. Price said. “And our focus right now is on shining a spotlight on what they’re doing and supporting them in the ways we can.”