A recent crackdown on students in Iran has come under criticism by university professors and others who hold President Hassan Rohani responsible for the pressure and are calling on him to take action.

More than 100 students were reportedly detained during protests over the economy in late December and early January that evolved into demonstrations against the establishment that included chants targeting Supreme Leader Ayatollah Ali Khamenei. Some of the detainees reportedly never took part in the protests, which spread to some 80 cities.

Two of the detained students, Sina Darvish Omran and Ali Mozaffari, were subsequently sentenced to eight-year prison terms after being convicted on charges including acting against national security, Iranian media and rights activists have reported.

Omran and Mozaffari, who were reportedly arrested by the Intelligence Ministry in December 2017 and held in solitary confinement, also face two-year bans from political and social-media activities.

At least three other students have been reportedly sentenced to prison, with their terms ranging from six months to one year and including bans on leaving the country.

More than 100 university professors have signed a letter to Rohani criticizing the recent arrests and sentences, stating that the crackdown had created concerns that "some are trying to silence dissenting voices in the universities."

"It seems that most of the detainees are individuals involved in legal activities, and perhaps some had criticized your government's work on campuses," the letter published on July 16 by Iranian news sites said.

"We want you to act upon your promises to defend the rights of the people, support a [safe] space for students for criticism, and protect [them]," the letter said.

The signatories called for a "secure" environment at universities, rather than a "securitized" one.

Earlier this month, more than 60 university groups across the country criticized pressure against students, calling in a joint statement for the release of student detainees, an end to their prosecution, and clarification of the role of the Intelligence Ministry, whose head is chosen by the president.

"Not only does the 'moderate' government of Hassan Rohani not react to the arrests, but the footprint of its Intelligence Ministry is seen in the arrests and the sentences," the statement said.

Students at several Iranian universities have protested the pressure against them in recent weeks, according to media reports and social media.

A video posted online on June 28 shows students at Tabriz University of Medical Sciences singing a protest song while holding signs such as one that read, "Students don't belong in jail."

The students are wearing mouth-covering masks, apparently to highlight the attempts to silence critics.

Rohani, who earned the '"relative moderate" moniker upon becoming president in 2013, has faced increased demands in his second term to resist pressure from hard-line conservatives who oppose his campaign promises to give Iranians more rights and lessen state interference in their lives.