Police fired rubber bullets at a group of around 40 activists, an AFP journalist reported, a day after the city governor's office banned the march citing safety and public order concerns.
Small groups gathered at Taksim Square but witnesses said a heavy police presence outnumbered the activists, and at least four people were detained.
It is the third year in a row that the march has been banned, and organisers denounced the move.
"We are here again to show that we will fight in a determined fashion for our pride."
In one of the biggest LGBT events in the mainly Muslim region, the 2014 Gay Pride parade in Istanbul drew tens of thousands of people.
Last year, with the city on the edge after bombings blamed on the Islamic State group and Kurdish militants, organisers were denied permission to march.
Riot police fired tear gas and rubber bullets to disperse protesters who defied the ban.
This year, the parade coincided with the first day of Eid, the festival marking the end of the holy Muslim fasting month of Ramadan.
City authorities banned the parade after threats from far- right and conservative groups.
Critics accuse President Recep Tayyip Erdogan of having overseen a creeping Islamisation since he came to power, first as prime minister in 2003 and then president in 2014.
He has repeatedly infuriated activists with his conservative comments on sex and family planning, but has generally steered clear of commenting publicly on gay issues.
Homosexuality has been legal in Turkey throughout the period of the modern republic but gay people in Turkey regularly complain of harassment and abuse.
"We are not alone, we are not wrong, we have not given up," the Pride Committee's statement said today.
"Governors, governments, states change and we stay. Threats, bans, pressures will not deter us ... We will not give up on," it added.
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