On Sunday, police spokesman General Saeed Montazerolmahdi said the morality police would resume notifying and then detaining women not wearing the Islamic headscarf in public.
In Tehran, men and women from the morality police could be seen patrolling the streets in marked vans.
The morality police had largely pulled back following the death of Amini in their custody last September, an incident that sparked nationwide protests.
Authorities struggled to contain mass protests calling for the overthrow of the theocracy that has ruled Iran for more than four decades.
The protests largely died down earlier this year following a heavy crackdown in which more than 500 protesters were killed and nearly 20,000 detained.
Since then, morality police have rarely been seen patrolling the streets. In December, there were even some reports — later denied — that they had been disbanded.
Many women choose not to follow the official dress code in the capital Tehran and other cities, but authorities insisted throughout the crisis that the rules had not changed.
Iran's clerical rulers view the hijab as a key pillar of the Islamic revolution that brought them to power and consider more casual dress a sign of western decadence.
Late on Saturday, police arrested Mohammed Sadeghi, a young and relatively unknown actor, in a raid on his home that he appears to have broadcast on social media.
Earlier, he had posted a video in response to another online video showing a woman being detained by the morality police. “Believe me, if I see such a scene, I might commit murder,” he said.
The website of the semi-official Hamshahri daily, which is affiliated with the Tehran municipality, said he was arrested for encouraging people to use weapons against the police.
The battle over the hijab became a powerful rallying cry last year, with women playing a leading role in the protests.
The demonstrations quickly escalated into calls for the overthrow of Iran's clerical rulers, whom the mostly young protesters accuse of being corrupt, repressive and out of touch. Iran's government blamed the protests on a foreign conspiracy, without providing evidence.
Several Iranian celebrities joined the protests, including prominent directors and actors from the country's celebrated film industry. Several Iranian actresses were detained after appearing in public without the hijab or expressing support for the protests.
In a recent case, actress Azadeh Samadi was barred from social media and ordered by a court to seek psychological treatment for "antisocial personality disorder" after appearing at a funeral two months ago wearing a cap on her head.