An Iranian film-maker has apologised after pranksters dressed as members of Islamic State entered a shopping centre in Tehran to promote his feature film.

A group of actors, some of whom had appeared in Ebrahim Hatamikia’s recently released Damascus Time, brandished fake guns, wielded swords and rode a horse past onlookers in the Kourosh shopping centre and cinema complex.

The stunt was met with a great deal of criticism on social media in Iran after reports suggested that some people, including children, had panicked. Pictures posted online also showed people taking selfies as the pranksters went up escalators. One is shown trying to connect the wires of a fake bomb.

Seventeen civilians were killed and 43 wounded last year in simultaneous Isis attacks on the Iranian parliament building and the mausoleum of Ayatollah Khomeini in Tehran.

In his apology, Hatamikia said he did not know the details of the publicity event for Damascus Time in advance. “I was under impression that someone is going to be in red beard standing outside Kourosh complex so that people can take pictures. I didn’t imagine there would be a horse, crowd and shouting inside the complex, I wasn’t aware,” he said.

The film tells the story of an Iranian father and son who are co-pilots on a cargo plane carrying humanitarian supplies for people in a Syrian war zone, but are later captured by Isis.

Hatamikia is well-known in Iran and his views are largely seen as sympathetic to the establishment. The award-winning Damascus Time has been lauded by the Iranian foreign minister and the commander of its Quds force, the Revolutionary Guards special forces unit that has been fighting in Syria.

The production company behind the film has received funding from the Revolutionary Guards.

Seyed Mahmoud Razavi, an Iranian producer, said the PR stunt at the shopping centre was “a big mistake and an insulting joke”. The Iranian journalist Mira Ghorbanifar tweeted that it was normalising violence.

Iran is a staunch supporter of Bashar al-Assad. It has been propping up his government since the conflict began, giving him crucial ground support, thanks to a combination of Hezbollah fighters, Shia volunteers from across the Middle East and members of the Revolutionary Guards. Russian and Iranian backing has swung the conflict in Assad’s favour, at the same time as the so-called caliphate of Isis has crumbled.