Turkish police in riot gear used tear gas, stun grenades and pepper spray to break up a crowd of several hundred people.
Protesters gathered to voice their anger at Friday's round-up of nearly a dozen pro-Kurdish lawmakers, including the two leaders of the People's Democratic Party (HDP).
They're also upset at the arrest of of journalists and executives of an opposition newspaper last weekend. The staffers were charged with links to the Kurdistan Workers party, or PKK, which is considered a terrorist group by Turkey, the United States and European Union.
Hundreds marched down the streets of Istanbul on Saturday, chanting "We will resist, we will win." Police issued several warnings via loudspeaker but were unable to disperse the crowd.
Officers then fired tear gas and aimed water cannons at the crowd as the protesters marched from Sisli, a district on the European side of Istanbul, to the headquarters of opposition newspaper Cumhuriyet.
A CNN crew saw more than a dozen protesters arrested. Police also chased demonstrators through standing traffic and down side streets and alleys as the situation escalated.
Pedestrians, including children, were caught in the middle of the confusion and were seen covering their faces and coughing from exposure to tear gas and pepper spray.
Some shoppers took shelter in stores, which locked their doors to keep crowds and tear gas from getting inside.
Journalists covering Saturday's protest also faced police intimidation. CNN crews on the ground in Istanbul witnessed a journalist being threatened with arrest. His phone was temporarily confiscated by an officer, who deleted more than a dozen photos and videos of the protest.
Party leaders detained
Early Friday, more than a dozen members of Parliament from the pro-Kurdish HDP were detained because they failed to respond to a summons by a prosecutor, according to a statement from the Prime Minister's office. State media reported several of the party's politicians were detained as part of a terrorism investigation, following raids on their homes.
HDP party leaders Selahattin Demirtas and Figen Yuksekdag were among those arrested, according to the state-run Anadolu news agency.
The HDP, Turkey's third-largest political party, also said its headquarters in Ankara was raided.
Authorities also blocked access to the WhatsApp messaging service, Twitter, YouTube and Facebook, according to TurkeyBlocks, an Internet monitoring group.
Ongoing crackdown after failed coup
Turkey's government responded with a heavy hand after a failed military coup last July. President Recep Tayyip Erdogan vowed to root out perceived enemies of the state and led an intense crackdown on government critics and the PKK, and those with alleged ties to US-based cleric Fethullah Gulen
, whom Turkey blames for the coup attempt.
Hundreds of military officers have been suspended, thousands of teachers have been dismissed, public servants sacked and media organizations shut down.
While ISIS is suspected in bombing attacks that have killed hundreds of people in Turkey, Friday's bombing is believed to be the first time the terrorist group has taken credit for an attack inside Turkey -- one of their primary jihadist recruiting grounds.
The Kurds are Turkey's largest ethnic minority. They have fought for equal rights and greater autonomy for decades -- and the PKK has carried out attacks primarily on Turkish government and military targets.