But the men were actually actors, who appeared on behalf of Iranian filmmaker Ebrahim Hatamikia, to promote his upcoming feature Damascus Time.
The footage showed some bystanders clearly knew it was a stitch-up, smiling at the actors while filming on their phones.
But the stunt has been slammed on social media, with many saying it was in poor taste considering the threat posed by Islamic State.
Two terror attacks were carried out in Tehran only a year ago, targeting the Iranian Parliament building and the Mausoleum of Ruhollah Khomeini. The incidents left 17 civilians dead and 43 wounded.
Hatamikia later said he was unaware of the stunt.
"I thought a person with a red beard (like ISIS militants) is going to stand outside the mall and let the fans take selfies with him. I didn't know there would be horses, screams, and crowds inside the mall," he said, according to Iran Front Page.
"The show was definitely beneath the dignity of my film," he added.
One clip filmed by one of the bystanders shows a parent shouting at the actors: "What if a woman or a child is shocked by your freaky show here? Who is responsible for such a stupid move? Who the hell did tell you to dress up like this?"
But this incident isn't the first of its kind.
Fake terror attacks have become something of a trend, with aspiring social media personalities — some with millions of subscribers — posting prank videos of themselves scaring the public with their elaborate stunts.
And the perpetrators are often westerners.
One video by YouTuber Joey Salads — real name Joseph Saladino — shows a man dressed in stereotypical Arab clothing dropping a steel box at random people's feet, shouting "Allahu Akbar!" and running away. The video has been viewed over 3.3 million times.
Earlier this year, British YouTube star Arya Mosallah sparked global outrage after throwing water in the faces of strangers. At the time, a crime involving genuine attackers throwing acid in victims' faces had tripled in frequency and was receiving extensive media coverage.
The 17-year-old ended up apologising following a widespread social media backlash, but told the BBC he would continue posting "extreme pranks".
"I'll push the boundaries until I get a million views... because what YouTubers like to see is views," he said. "Honestly they don't care about the dislikes or the comments, nothing like that, as long as they get the views they want that's it. They're happy. And I was happy with the views I was getting."
In early 2013, less than a year after a gunman murdered audience members at a screening of The Dark Knight Rises, the Goodrich Capital 8 Theater staged a stunt for its Iron Man 3 screening in which a man with a gun walked into the cinema.
He was actually part of a cosplay group who had dressed like members of S.H.I.E.L.D., the movie's fictional government security agency, but police were called and the move sparked an online backlash.
The theatre manager issued an apologetic statement, insisting it was "not a publicity stunt" and "some people didn't realise it was for entertainment purposes only".
Evidently there's no such thing as bad publicity — and that couldn't be more applicable in the viral age.
