The police officers also barred people from entering Istiklal Avenue and turned back all those thought to be linked to the banned event.
Smaller gatherings of LGBT activists are believed to be held across the city simultaneously with people reading out a statement of defiance published by an LGBT group.
According to Turkish media outlets and several pro-LGBT twitter accounts, police fired plastic bullets at a group of around 40 activists in the country's largest city.
Tear gas and rubber pellets marred Pride rallies in Istanbul Sunday as LGBTQ supporters took to the streets in defiance of a parade ban.
"Just to be surrounded by hundreds and thousands of people going "Yeah" for hours, is incredible".
The Pride organizers said the threats should be dealt with rather than curb demonstrations.
'The fact that the existing political power is not making the necessary changes in the constitution, and the fact that they have discourse against us might encourage people who are already transphobic, ' said Seyhan Arman, a 37-year-old transgender woman and performer.
In Minneapolis, organizers of Sunday's Twin Cities Pride Parade initially asked the police department to limit participation following the acquittal of police officer Jeronimo Yanez in the death of Castile.
Activists for lesbian, gay, bisexual, trans and intersex rights had vowed to hold the event on Sunday despite being it being officially forbidden by the governor's office for a third year running.
City officials claim there has been no official application for this year's march, but organizer Lara Ozlen from the parade's organizing committee told the AFP news agency this was a "lie".
This year, the parade coincides with the first day of a festival celebrating the end of the holy Muslim fasting month of Ramadan. I want to say thank you to Marsha P, Johnson who reportedly threw the first brick.
A statement released by the organisers yesterday morning said: 'We are not scared, we are here, we will not change.
"Even if the government permits it, we will not let them walk", said Kürşat Mican, Istanbul head of Alperen Ocakları during a program on KRT TV.
It was the second year in a row that it had been banned, citing fears over the safety of marchers and tourists because of threats from right-wing ultra-nationalist groups. It also insists that perpetrators of hate crimes are prosecuted.