Six young Iranians have been arrested after they uploaded a video of themselves dancing throughout Tehran to Pharrell's "Happy."

"Happy in Tehran" was uploaded to YouTube last month and garnered more than 165,000 views before being made private. It shows three men and three women -- all unveiled -- looking, well, happy as they dance and lip-synch to Pharrell's hit.

But authorities in Tehran are calling the video "vulgar," and all six were arrested and forced to formally apologize on state television. (Under Islamic law, women are required to cover themselves from head to toe in public, a rule monitored by "morality police.")

"After a vulgar clip which hurt public chastity was released in cyberspace, police decided to identify those involved in making that clip," Tehran police chief Hossein Sajedinia announced on Tuesday (May 20), according to ABC News. "Following a series of intelligence and police operations and after coordinating with the judiciary, all the suspects were identified and arrested."

The clip was one of many "Happy" covers made by fans worldwide in celebration of the UN's International Day of Happiness.

In an interview last month, one of the dancers in the video, named Neda, said the video was meant to show that young Iranians "have moments of joy and happiness even though they live with many difficulties."

“We wanted to tell the world that the Iranian capital is full of lively young people and change the harsh and rough image that the world sees on the news,” she said.

"It is beyond sad that these kids were arrested for trying to spread happiness," Pharrell wrote on his Facebook page on Tuesday.