Turkish Foreign Minister Mevlut Cavusoglu criticised Germany after two German towns stopped Turkish ministers from holding meetings with supporters of President Erdogan. The spat appears to have triggered a bomb hoax on Friday.
Turkey on Friday accused Germany of "double standards" after two German towns stopped Turkish ministers from speaking at meetings of supporters of President Recep Tayyip Erdogan.
Turkish Foreign Minister Mevlut Cavusoglu also told its NATO partner that it must "learn how to behave."
"The obstruction of meetings in Germany is a sign of how much Germany and the West are displaying double standards," Cavusoglu said.
Justice Minister Bekir Bozdag was due to speak in Gaggenau to Erdogan supporters as part of Ankara's effort to rally support among Germany's estimated 1.5 million Turkish citizens for an April referendum on constitutional change that would expand the powers of the Turkish presidency.
Authorities said they cancelled the event because the venue was too small for the expected crowd.
Germany is home to the largest Turkish expatriate community in the EU, numbering around three million people.
Cavusoglu's comments reflected a broader souring of ties between the two countries, tested most recently by Turkey's arrest earlier this week of Deniz Yucel, a Turkish German dual national who is a correspondent for the prominent Die Welt newspaper.
On Friday, Gaggenau's authorities evacuated city hall after receiving what turned out to be a hoax bomb threat.
The city hall in the southwestern German town was evacuated after a bomb threat was phoned in. A search of the building did not turn up any explosives.
"After a thorough assessment, nothing suspicious could be found," police said, allowing people back into the building.
Asked whether the threat was linked to the cancellation of Bozdag's appearance, mayor Michael Pfeiffer said, "We presume this at the moment, but we don't know for sure."
Gaggenau, a town of around 30,000 inhabitants, was one of two German venues to block speeches by Turkish politicians.
The city of Cologne said security concerns prompted it to cancel an event where Turkish Economy Minister Nihat Zeybecki was to speak on Sunday.
"Haven" for terrorist groups
On Friday, Bozdag said Germany had become a haven for terrorism.
"Germany today has become a shelter for all those who commit crimes against Turkey, the PKK, FETO, DHKP-C members. Those who carried out the coup and everyone who commits crimes against Turkey have fled there," he said.
Gerrmany's foreign ministry on Friday it was not involved in the decision to cancel Bozdag's appearance.
"It was a decision that the German federal government did not influence in any way, and could not have influenced, because it is a matter of state and local law over which we have zero influence," spokesman Martin Schaefer said.
He said Germany's ambassador to Turkey Martin Erdmann stressed that in a "serious but friendly" discussion with Turkish authorities after Ankara summoned the German envoy on Thursday.
Schaefer said Berlin would do everything it could to maintain an open dialogue with Turkey despite tensions over a range of issues, including Turkey's arrest of the Die Welt journalist.
Germany's Chancellor Angela Merkel also weighed in on the spat on Friday, reiterating that local authorities cancelled the Turkish ministers' appearances and that Germany remained committed to freedom of expression. Merkel also criticised Monday's arrest of Yucel and what she said were restrictions on journalists in Turkey.
Germany is wary of rising tensions, seeking continued Turkish commitment to procedures preventing large movements of refugees through Turkey to Europe.