"The armed attack on the vulnerable people in the first hours of the new year hurt our nation deeply. There is no difference whether this inhuman massacre is carried out at a bazaar, a place of entertainment or a place of worship," Gormez, head of the Religious Affairs Directorate, said in a written statement that described the attack as "savagery".
"Terrorists do not target places, but people, nations and the whole humanity. Terrorism cannot be tolerated whoever or whatever it comes from," Gormez added.
Earlier, Governor Vasip Sahin said the attack in Ortakoy, Besiktas, was “cruel” and an “act of terror”.
“At 1.15 a.m., a terrorist carrying a long-barreled weapon martyred the police officer waiting outside, and then martyred another citizen to enter” the club, he said.
“He then carried out this violent and cruel act by spraying bullets on innocent people who were celebrating the new year," Sahin said.
An investigation is underway and the governor’s office would provide further updates, he added.
The attack comes three weeks after twin bombings in Istanbul killed at least 45 people, mostly police officers.