"That is an unprecedented act of interference in the sovereignty of our country," Gabriel told the RedaktionsNetzwerk media group.
"Erdogan's interference in Germany's electoral campaign shows that he wants to incite people in Germany against each other," he said.
Gabriel urged Germans to push back by turning up in strength at the polls and voting for parties that champion democracy.
"Let's show those who want to play us against each other that we will not participate in this evil game," he said.
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Atila Karaborklu, the co-chairman of Germany's Turkish Community association, accused Erdogan of "seeking to divide German society".
His aim is "to hurt German democracy," charged Karaborklu.
Erdogan today called on Turks living in Germany not to vote for the two parties in Chancellor Angela Merkel's ruling grand coalition or the Greens in next month's legislative elections, calling them "enemies of Turkey".
Upping the stakes in a intensifying row with Berlin, Erdogan said ethnic Turks in Germany should not cast their ballots either for Merkel's Christian Democratic Union (CDU), Gabriel's Social Democratic Party (SPD), or the Greens.