Six Iranians have been arrested by police and shown on state television after posting a version of Pharrell Williams' hit song Happy on YouTube.
The amateur video shows three young men and three unveiled women dancing to the tune on Tehran's streets and rooftops.
"We have made this video as Pharrell Williams' Fans in 8 hours, with iPhone 5S. "Happy" was an excuse to be happy. We enjoyed every second of making it. Hope it puts a smile on your face," reads a message at the end of the video, titled Happy We are from Tehran.
But the group were detained when the video, which has been viewed thousands of times, came to the attention of Tehran's police force.
Police chief Hossein Sajedinia was quoted by the ISNA news agency as saying: "After a vulgar clip which hurt public chastity was released in cyberspace, police decided to identify those involved in making that clip.
"Following a series of intelligence and police operations and after coordinating with the judiciary, all the suspects were identified and arrested."
ISNA said the detainees had "confessed to their criminal acts".
Pharrell Williams' song is from the film Despicable Me 2
State television aired blurred pictures of the video and then showed the six with their backs turned to camera.
Williams, whose song from the film Despicable Me 2 has been one of the biggest hits of the year, commented on the arrests on Twitter.
It's beyond sad these kids were arrested for trying to spread happiness http://t.co/XV1VAAJeYI
— Pharrell Williams (@Pharrell) May 21, 2014
Conservatives say many young Iranians are abandoning Islamic values and turning to a more Western way of life.
Under Islamic law, in force in Iran since the 1979 revolution, women must cover themselves from head to toe.
More than a decade ago a "morality police" unit was formed to verify that women scrupulously respect the dress code in public.
The internet is also heavily filtered in Iran, with the authorities blocking access to popular social networking sites.
Civil liberties and women's rights have returned to the forefront since President Hassan Rohani's election last June.
Mr Rohani, a moderate, had campaigned for greater cultural and social freedoms in the Islamic republic, specifically urging police tolerance over the veil.
