According to the Süddeutsche Zeitung Saturday's raids had originally been scheduled for the end of October, but was moved up when at least one of the Isis suspects began to suspect a police operation against them was being planned.
A Lebanese national, Kassam El R., is suspected of supporting a terrorist organization by shipping 7,500 winter boots, 6,000 military parkas and 100 military shirts with a value of €130,000 to the terrorist organization Ahrar al-Sham.
Two men living in Aachen, Kamel Ben Yahia S. from Tunisia and Yusup G. from Russia are accused of smuggling a 17-year-old German to Syria via Turkey to fight for Isis.
Kamel Ben Yahia S. is also accused of funnelling €1,100 worth of clothing and €3,400 in cash to terrorist groups in Syria.
All four of those arrested were living in North Rhine-Westphalia. The homes raided were all connected to Salafist community.
Raids were carried out in seven states, including Baden-Württemberg, Hamburg, Hesse, Rhineland-Palatinate, Saxony, Schleswig-Holstein, as well as North Rhine-Westphalia.
All four arrested are facing court processes in Karlsruhe.
Germany officially made support for Isis illegal in September.