The Ankara governorate said in a statement that all such meetings had been prohibited until November 30, in line with the state of emergency imposed in the wake of the failed July 15 coup.
It said that the decision was taken "to ensure people's safety and public order".
The governorate, which is responsible for security throughout the capital and the wider province, said it had received intelligence "that banned terror organisations were preparing actions in our province".
The capital has been hit repeatedly over the last 12 months by attacks blamed on jihadists and Kurdish militants.
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One hundred and three people were killed on October 10, 2015 when suicide bombers said to be linked to Islamic State (IS) jihadists blew themselves up in a crowd of pro-Kurdish peace activists planning to hold a rally outside Ankara's main train station.
At least 30 were killed on February 17, 2016 and 37 more lost their lives on March 13, 2016 in bombings claimed by a radical Kurdish armed group.
A suspected Islamic State suicide bomber blew himself up at the weekend in the southeastern city of Gaziantep during an anti-terror raid, killing three police officers, officials said.
A few hours later, a second suicide bomber detonated his explosives, killing himself but without causing any further fatalities.