Organisers describe ban as a “flagrant violation of the constitution” and say they will take legal action.
Turkish police have fired rubber bullets and tear gas to break up a banned rally by the LGBT community in central Istanbul.
Several hundred riot police surrounded the main Taksim Square on Sunday to prevent the event called “Trans Pride” from taking place. The rally was to kick off the LGBT – Lesbian, Gay, Bisexual and Transgender – week in Turkey.
Istanbul’s governor had banned the LGBT from holding rallies this week, citing security concerns.
As the police swooped in on the rally of a few hundred people, the crowd fled into nearby streets.
Demonstrators unfurled a rainbow flag, a symbol of the LGBT community, and then tried to read a statement but were prevented from doing so by the police.
Turkish media reported that at least two people were arrested.
Istanbul authorities said on Friday that they had banned the annual Pride parade, the main rally of the week, set for June 26 to “safeguard security and public order”.
The annual Pride parade and Pride Week Istanbul (June 20-26 this year) have taken place since 2003, attracting tens of thousands of people in recent years, with a reported 100,000 participants in 2013.
Police broke up the 14-year-old rally for the first time last year. Both this year and last year, events overlapped with the Muslim fasting month of Ramadan.
There has been a string of bombings around Turkey over the past year, some of them blamed on the Islamic State of Iraq and the Levant (ISIL) group, others claimed by Kurdish fighters.
The annual Pride parade in Istanbul came under threat from ultra-nationalist and conservative groups who pledged to do “what is necessary” to stop the event.