Islamist militants have told Christians in a northern Syrian city that they will guarantee their safety. But there’s a catch.

Make that a lot of catches.

Christian residents of Raqqa, once one of the nation’s most liberal cities, will have to pay as much as 17 grams of gold per adult male in an annual payment, the extremist group the Islamic State of Iraq and Syria (ISIS) said in a statement posted online this week.

The group is also forbidding the city’s Christians from repairing or refurbishing their churches and monasteries, said the statement, which has been circulated in the city, according to Syrian activists.

The list of constraints imposed by the militants also limits Christian worship, business activities and alcohol consumption.

A Syrian boy attends school in the Turkish town of Kilis on December 17, 2012, as a group of volunteer Syrian teachers joined forces and opened a school for Syrian children, some of whom had been out of school for over a year. The school, on the ground floor of a three-storey building in southwest Kilis, lacks all but the the most basic of supplies while all the teachers work for no pay in cramped classrooms where five children often squeeze into desks made for three.

video

Related videoU.N. education plan for Syrian refugees

syria rebel leader killed wedeman lklv_00002201.jpg

video

Related videoAl Qaeda linked Syrian rebel head killed

Syrian rebels inspect a tank left behind by government forces in the outskirts of Raqqa on July 1, 2013.

video

Related video2013: Al Qaeda tightens grip on Syrian city

The heavy restrictions are perhaps unsurprising coming from ISIS, which hasbroken away from al Qaeda and is fighting with other rebel groups in Syria.

Activists told CNN in November thatRaqqa was becoming increasingly conservative after ISIS began imposing hardline Islamist law there and meting out harsh punishment to those who don’t follow orders.

Locals started calling the city Tora Bora and saying it felt as if the Taliban of Afghanistan had taken over.

ISIS’s new set of restrictions on Christians has drawn criticism from the Syrian opposition and even a radical Muslim cleric.

Louay Safi, a spokesman for the Syrian Coalition, said ISIS’s treatment of non-Muslims was un-Islamic.

And the radical cleric, Abu Qatada, who is on trial in Jordan over terrorism charges, told CNN Arabic on Thursday that the militants didn’t have the right to offer protection and demand payment from Christians because they weren’t yet empowered to govern Syria.

It’s unclear how many Christians remain in Raqqa after years of bloody civil war in Syria.

Since ISIS began cracking down on dissent in Raqqa, many activists and residents have fled the city.

Other things the extremist group have forbidden Christians in Raqqa from doing include:

– Exposing crosses or their books to Muslims;

– Making any recitations or ringing any church bells that can be heard by Muslims;

– Trading pigs or alcohol to Muslims or in their markets;

– Drinking alcohol in public.

READ: CNN Exclusive: Inside Syrian town living under al Qaeda reign of fear

READ: Pro-government forces find a haven at Syrian town’s Christian monastery

CNN’s Salma Abdelaziz and Hamdi Alkhshali contributed to this report.