The 38-year-old, who had two daughters, was reportedly gunned down in broad daylight by an assassin using a silenced gun in Gaziantep, a Turkish city close to the Syrian border.
The director had made two documentaries for Raqqa is being Slaughtered Silently (RBSS), a group of journalists and activists who risk their lives to film and report on daily life in Raqqa.
The Syrian city became the de facto capital of the so-called Islamic State (IS) after the Islamist group captured it in 2013.
Mr Jerf made two recent films – one about the death of activists in Aleppo, and the other about the work of RBSS.
He was also the editor of Hentah, a monthly magazine devoted to recording the ordinary lives of Syrians forced to live under the rule of IS.
His family had reportedly been granted asylum in France and were planning to head there this week.
Mr Jerf’s death comes just a week after fellow RBSS journalist Ahmad Mohammed al-Mousa was killed in Syria.
In October another member of the group and a friend were found beheaded in another Turkish town.
RBSS won an International Press Freedom Award for their work earlier this year.
The Committee to Protect Journalists said at least 85 journalists hd been killed covering the Syrian conflict and more than 90 had been abducted.