Russia is trying to destabilise German society and the state with propaganda campaigns and cyber attacks, Germany's domestic intelligence agency said.
The blunt warning from Germany's BfV agency comes less than a year before the country is expected to hold a general election.
Agency chief Hans-Georg Maassen said in a statement that "there is growing evidence for attempts to influence the federal election next year".
His agency has seen an increase in "aggressive cyber-espionage" targeting German politicians.
Russia has been blamed for the hacking and release of Democratic National Committee emails before the US presidential election.
Mr Maassen said "automated opinion forming" with so-called bots could be used to spread fake news on social media.
Russia has previously strongly denied its involvement in orchestrating cyber attacks on foreign soil.