The German Left Party's Sahra Wagenknecht accused Turkish President Recep Tayyip Erdogan of using being the "godfather of terrorism."
Demonstrators in Bern held up a sign reading "Kill Erdogan with his own weapons."
Tensions continue to rise between Turkey and Germany as Erdogan campaigns for his constitutional referendum.
Europe-Turkey relations have soured following the president's crackdown on opponents and spats over referendum rallies.
Erdogan said in a speech in Istanbul on Sunday: "Merkel, now you're applying Nazi methods."
Germany and Turkey have been locked in a deepening row over the Turkish government's attempts to hold rallies in European countries.
Demonstrators fear the April referendum will give the Turkish president license to go after Kurds if voters approve it.
Diplomatic rows could have serious consequences for one of the EU's most important policies.
Ankara has cut high-level ties with the Netherlands in an escalating dispute.
Ankara's military intervention in Syria has run afoul of U.S. and Russian interests.
Dutch government barred Turkish ministers from speaking in a diplomatic row over Turkey's attempts to rally Erdogan supporters overseas.
The Netherlands became the latest European country to restrict campaigning for Erdogan's drive for sweeping new powers.
The Turkish president recalls the Nazi era to describe Germany's decision to cancel pro-Erdogan political rallies planned by the country's Turks.
The town of Gaggenau blocked a talk due to be given by the Turkish justice minister.
Opponents fear a surge in authoritarianism as President Erdogan seeks more power
Burhan Ozbilici captured the immediate aftermath of the assassination.
The incident took place near the Islamic State-held city of al-Bab in northern Syria.
Instability in Iraq threatens U.S. foreign policy interests in the Middle East.
The CIA has not confirmed the visit, but officials and media expect Pompeo Thursday.
The German chancellor must preserve a deal with Ankara that limits refugee flows into Europe.
Relations between the two countries soured after the Israeli commando raid on the Mavi Marmara in 2010.