Police in the southwestern city of Stuttgart confiscated computers, data storage devices, smartphones and documents, said the interior minister of Baden-Wurttemberg state, without reporting any arrests.
"We do not tolerate associations that advocate the use of violence to promote religious concerns and collect donations for terrorist groups," said the minister, Reinhold Gall.
He charged that radical preachers and fundamentalist Islamists, mainly from western Balkan states, had frequented the Islamic Educational and Cultural Centre Mesdschid Sahabe.
Of about 50 people who had travelled to Syria from Baden-Wuerttemberg to join the fighting, at least 10 had been visitors of the mosque, and three of them had since died, he said.
The centre -- which was previously raided by police in March to gather evidence -- had now been closed and disbanded and its property confiscated, added the minister in a statement.
"The association supports, in the form of the so-called Islamic State, an Islamist group that carries out religiously- motivated attacks against persons and property," he charged.
"Through the association, donations have been collected for terrorist groups and fighters recruited for the conflict in Syria. In addition, the association and its members glorify jihad and religiously motivated terrorism."