Foreign Minister Sigmar Gabriel said that if Ankara were to bring back the death penalty, the move would be "synonymous with the end of the European dream" and mark the end of decades of negotiations to enter the European Union.
It is in Turkey's "own interest" not to distance itself further from Europe, said Gabriel in an interview in the Bild mass circulation daily to be published Tuesday.
"Any decision (about joining the EU) will not be on the agenda anytime soon. At any rate, joining would not work right now," he added, noting that Turkey must decide which direction to take.
Immediately after winning a nail-biting vote on extending his powers, Turkish President Recep Tayyip Erdogan mooted a second referendum on bringing back the death penalty, which would sound the death knell for the country's EU ambitions.
"If (a bill) comes before me, I will approve it. But if there isn't support (from opposition MPs) ... then we could have another referendum for that," Erdogan said, as his supporters chanted for its reintroduction.
Turkey abolished the death penalty in 2004 as part of its bid to join the European Union and Brussels has made it clear that any move to restore it would scupper Ankara's efforts to join the bloc.
In an earlier joint statement with Gabriel, Chancellor Angela Merkel urged Turkish authorities to "seek respectful dialogue with all political and social forces in the country after this tough election campaign."
Merkel said Germany "respected the right of Turks to decide on their constitution" but added that "the close result shows the extent to which Turkish society is deeply divided."
Ties between Germany and Turkey plunged during the referendum campaign when Erdogan accused authorities of acting like "Nazis" by banning ministers from campaigning to Germany's huge ex-pat Turkish community.
The 'Yes' camp won with 51.41 percent in Sunday's vote on giving Erdogan sweeping new powers, according to near-complete results, but angry opposition groups have cried foul and demanded a recount.
International observers from the Council of Europe and the Organisation for Security and Cooperation in Europe (OSCE) said the referendum campaign was conducted on an "unlevel playing field" and the vote count itself was marred by the late procedural changes that removed key safeguards.