Germany employs many Turks, who started coming to Germany even before the EU was around, due to an agreement between Germany and Turkey to provide laborers for the German economy. Many of these people settled in Gemany and brought their families too. The Germans do not like the Turks, as they tend not to like other "others". Indeed, Germany is the main opposition for having Turkey join the EU. The fact that Germany outlaws a Turkish-German organization makes sense when viewing their own self-perceived interests. They remove another group from ever getting citizenship in Germany, and can list another reason why Turkey should not join the EU. This is not to criticize their anti-Turkish policy, but just to let Israelis understand that the German attitude is motivated by the "hatred of Haman" rather than by the "love of Mordechai".
Israeli official: Der Spiegel report is an attack on Merkel's ties with Netanyahu (Haaretz)
from the article: Germany outlaws charity over alleged Hamas links