BERLIN: The raids began at 6:30 am (0430 GMT) and targeted, among others, a 51-year-old Moroccan suspected of recruiting for the jihadists, police said in a statement.
A 19-year-old Macedonian thought to be currently in Syria is also suspected of involvement in the recruitment drive, it said.
“We are looking for evidence to see whether these allegations are true,” a police spokesman said. No arrests were made.
One raid was conducted at an association linked to a mosque in Berlin’s central Tempelhof district, the spokesman said. Seven homes were also searched.
An AFP photographer saw police leaving the building housing the mosque carrying bags and computers seized as evidence.
Police escorted a fully veiled woman out of the building and two small children.
The police spokesman said investigators had been working on the probe for six months and began planning the raid two weeks ago.
“We have no indications that anything was being planned in Germany,” he said when asked about indications of any plot to attack targets here.
But people who go to fight in Syria “gain experience of violence there and one day or another can return to Berlin”, he said.
He added that there was no link to an attack last Thursday in which an Iraqi man with a jihadist background stabbed a German policewoman before officers shot him dead in Berlin.
Germany has been spared a major Islamist attack, unlike many of its European neighbours, but the country has been called a potential target in Islamic State propaganda.
In August, two German-speaking jihadists claiming to belong to IS threatened Germany with attacks in an execution video broadcast online.
German intelligence estimates that some 600 Germans have joined jihadist groups in Syria and Iraq.