BERLIN — Germany on Friday announced a ban on activities that support the Islamic State in Iraq and Syria, including any displays of its black flag, as part of an effort to suppress the extremist group’s propaganda and recruitment work among Germans.

The ban was announced amid a growing Western-led drive to galvanize countries around the world, but particularly in the Middle East, to destroy the group, which has seized parts of northern and eastern Syria and northern Iraq and has become known for its brutality.

Germany’s crackdown reflected concern among officials about ISIS’s appeal in the country. About 450 Germans are believed to have departed for Syria as ISIS recruits, punctuating fears that they could return to Germany radicalized and dangerous. Under the new restrictions, all displays of support for ISIS, and all efforts aimed at enticing Germans to join the group, are prohibited.

“Germany is a true democracy, and there is no place here for a terror organization directed at the constitutional system and the belief in understanding among different peoples,” Thomas de Maizière, the interior minister, said in a statement announcing the ban.