yes there are, they are called "Langsamfahrsignale"
http://stellwerke.de/signal/deutsch/lf.html
Lf 1,2 and 3 are for temporary speed restrictions
Lf 1 is placed 1000m ahead of Lf2 and tells the driver to slow down
Lf 2 is placed at the beginning of the Speed limit
Lf 3 marks the end of the speed limit, the driver may accelerate to line speed again
Lf 4 and 5 are used for small routes, when the trackbed is bed, or a level crossing has to be passed slowly
Lf 4 is placed 1000m ahead of Lf4 and tells the driver to slow down
Lf 5 is placed at the beginning of the Speed limit
in this sign, the end of the Speed Limit is not marked.
Lf6 and 7 are used for Signalling a new Line Speed
Lf 6 is placed 1000m ahead of Lf7 and tells the driver to slow down
all signals below Lf7 are signals of the former Reichsbahn and are only used in East Germany