Germany's ambassador to Turkey was summoned by the Foreign Ministry on Monday -- the second time in a week -- according to diplomatic sources.
The sources, speaking on condition of anonymity, did not specify the reason why Martin Erdmann was called.
The summoning had been planned in advance but was carried out on Monday because Erdmann had been outside of Ankara, the sources added.
Germany's foreign ministry said it was the 17th time its envoy Martin Erdmann had been summoned, underlining the divisions at a time when European powers are counting on Turkey to help contain migrant flows, and to confront Daesh militants over its borders with Iraq and Syria.
Monday's summoning of Erdmann for the second time in such a short period was described as a "coincidence".
The German diplomat was also summoned on Saturday over a pro-PKK event held in the western German city of Cologne.
At the event, about 3,000 pro-PKK demonstrators gathered at Deutzer Werft Square as part of a so-called international Kurdish festival.
Germany has criticised mass arrests carried out in Turkey since last year's failed July 15 coup, which was orchestrated by Fetullah Gulen and his followers, and demanded the release of around a dozen German or Turkish-German citizens arrested in recent months.
Chancellor Angela Merkel, who is seeking re-election on Sunday, has called for Turkey's EU accession talks to be called off. Germany also says it is limiting arms sales to Turkey.
Turkey says Germany has ignored Ankara's requests for the extradition of suspects it believes are linked to the putsch and accused Berlin of using Nazi-like tactics by banning pro-Erdoğan rallies on German soil.
Turkey, which says the killings of Christian Armenians during World War One do not amount to genocide, already recalled its ambassador to Germany after parliament passed the resolution last year.
The PKK -- listed as a terrorist organization by Turkey, the U.S. and EU -- resumed its armed campaign against Turkey in July 2015. Since then, it has been responsible for the deaths of around 1,200 Turkish security personnel and civilians.
