Police in Iran have arrested six young people for a video posted online of them dancing to Pharrell Williams’ hit song Happy.
Images of the six were also shown on state television as a public warning.
The song has sparked similar videos all over the world, with people dancing down streets in smiling choreographed crowds.
But in the Islamic Republic of Iran some view the fad as promoting western culture, while laws ban women from appearing in public without the hijab headscarf. Iran also bans some internet websites.
On Twitter, Williams posted a link to a story about the arrests and wrote: “It’s beyond sad these kids were arrested for trying to spread happiness.”
In the Tehran video, three young men and three young women dance on a roof, stair, drive and an apartment, wearing sunglasses and silly clothes while laughing.
Tehran police chief Hossein Sajedinia confirmed on state TV late on Tuesday six people had been detained. State TV also aired blurred pictures of the video and then showed the six with their backs to the camera. Mr Sajedinia said the video clip “hurt public chastity” and prompted police to launch an investigation.
“They were identified and arrested within six hours,” he said.
The online video includes the participants’ first names in a credit roll with out-takes.
Those arrested said on the TV broadcast the video had been posted online without their permission. “They told us this video won’t be released anywhere and it was for our own pleasure,” one of the women said.
Another detainee said: “They invited us to appear on the video to practise acting.”
It was not clear if the six faced criminal or civil charges or had lawyers.
Mr Sajedinia warned all young Iranians that police will confront those who challenge Islamic norms.
The arrests come as hardliners challenge moderate president Hassan Rouhani as he negotiates a nuclear deal with world powers. Mr Rouhani campaigned for cultural and social freedoms during the presidential election last year and spoke on Saturday about the internet.
“We should see the cyberworld as an opportunity,” he said. “Why are we so shaky? Why don’t we trust our youth? “
Hardliners accuse him of letting “decadent” western culture spread unhindered.