Steffen Seibert, spokesman to German Chancellor Angela Merkel, said on Monday that the Bundestag - Germany's lower house of parliament - "had reached a sovereign decision."

"That must be respected," he added.

The comments from Berlin on Monday came in light of Turkey's reaction last week to Germany's decision to pass a resolution which refers to the mass deaths of 1.5 million Armenians under the Ottoman Empire as "genocide."

As the successor state to the Ottoman Empire, Turkey officially denies that the events that started in 1915 amounted to genocide. Ankara's official line is that ethnic Armenians represented a fifth column backed by Russia during World War I, and that the mass deportation and accompanying Armenian deaths were not premeditated or intentional - a key requirement in the legal definition of genocide.

Some 1.5 million people were killed in the 1915 Armenian genocide under the Ottoman Empire

Following the Bundestag's "overwhelming" vote in favor of the "genocide" resolution, Ankara recalled its ambassador from Berlin, with Turkish President Recep Tayyip Erdogan vowing to "never accept the accusations of genocide."

"First you need to answer for the Holocaust, then for the murder of 100,000 people in Namibia," Erdogan said.

The Turkish president also accused 11 German MPs with Turkish roots who backed the resolution of supporting "terrorism" by the banned Kurdish Workers' Party (PKK), and demanded "blood tests" to see "what kind of Turks they are."

Ankara's mayor, Ibrahim Melih Gökcek, later tweeted a collage of the 11 politicians, with the hastag #TheTraitorsMustLoseTheirCitizenship, claiming that they had "stabbed us [Turkey] in the back."

In response to the allegations, Seibert said on Monday that while Berlin also considers the PKK a terrorist group, "to associate individual members of parliament with terrorism is utterly incomprehensible to us."

Death threats

Among the 11 MPs was Green party co-leader, Cem Özedemir, who also instigated the vote on the resolution. The politician has since been placed under police protection after receiving anonymous death threats. The 50-year-old from Bad Urach in western Germany is the son of Turkish immigrants.

Speaking on Monday, Özdemir said that he wouldn't let himself be intimidated by Erdogan's verbal attacks.

"The votes in the German Bundestag aren't made depending on which authoritarian leaders are happy and which ones aren't," he said.

'This has gone too far'

During an interview with German news program "Tagesschau" on Monday, fellow Green politicians Özcan Mutlu said he had received "hundreds if not thousands of emails with messages of hate or death threats."

"As an MP, insults and threats have started to become normal," he said. "But this takes things to a new level."

Mutlu, who also appeared on the tweet posted by Ankara's mayor, called on the German chancellor to take a stand against Erdogan and "make it clear that this has gone too far."

Merkel's diplomatic relationship with Turkish President Recep Tayyip Erdogan has come under increasing scrutiny in recent months, with critics accusing her of ignoring Turkey's human rights record and worsening press freedom in order to win Ankara's cooperation in the implementation of the EU refugee deal.

Social Democrat (SPD) and Integration Minister Aydan Özoguz also condemned the threats on Monday.

"The death threats against us MPs are absolutely unacceptable and shock me deeply," he said.

"I expect parliament to clearly show its solidarity with us and to not leave us here alone," Özoguz added.

Solidarity from Bundestag and Turkish community

Seemingly in response to the calls for support, Christian Democrat (CDU) and Bundestag President Norbert Lammert said on Monday that he wanted to "reiterate the lower house of parliament's solidarity with the threatened colleagues."

Despite broadly opposing the "genocide" vote, Germany's Turkish community has also criticized Ankara and Erdogan's supporters for the pressure which has been placed on German lawmakers of Turkish origin.

"We find death threats and demands for blood tests abhorrent," said chairman of Germany's Association for the Turkish Community, Gokay Sofuoglu.

"I think the era when people were defined by their blood ended in 1945. This is absolutely out of place," he added.

Turkish President Recep Tayyip Erdogan has condemned the 11 German MPs with Turkish roots who backed the resolution

The growing tensions between Germany and Turkey have come at a critical time for both countries as they seek to fully implement the recently-agreed EU refugee deal which seeks to control the flow of migrants into Europe.

Diplomatic ties were also put under further strain in late March after German comedian Jan Böhmermann broadcast a poem mocking Erdogan on television. The verse, which led to legal proceedings against Böhmermann, accused the Turkish leader of bestiality and watching child pornography.