Police officers conducted a series of early-morning raids on Wednesday on 19 properties across the country, including in Berlin, while a coordinated search was carried out on a building in the Netherlands.
German prosecutors allege those detained have been acting as “financial intermediaries” in a network that supports ISIL terrorists in Syria, The National reported.
The seven arrested, who hold German, Turkish, Moroccan and Kosovan citizenship, are also accused of breaking export laws.
Four of the arrests were made in North Rhine Westphalia, with one each in Baden-Wuerttemberg, Rhineland-Palatinate and Bremen.
Searches were carried out in properties in Berlin, Bavaria, Hamburg, Hesse, Thuringia and Lower Saxony.
Prosecutors said the crackdown was linked to numerous investigations of people accused of donating to ISIL, in which more than 90 other properties were being investigated by police.
Officials say donations are being made to strengthen ISIL by helping to ensure the delivery of supplies to terrorist members held at two camps in northern Syria. The nature of those supplies was not specified.
At least €65,000 ($69,000, £56,000) has been transferred to Syria by the financing network, prosecutors claim.
MP/PR