Attackers threw Molotov cocktails at a synagogue in the western city of Wuppertal in the early hours of Tuesday in an apparent attempt to burn it down.
A neighbour alarmed police after spotting flames near the Bergische Synagogue in Gemarker Straße in the eastern district of Barmen at around 2.15 am.
Police said they believed three young arsonists had thrown several Molotov cocktails in the direction of the synagogue doors. Officers found broken bottles on the ground at the entrance, police said in a statement.
One 18-year-old man was arrested in connection with the attack.
No one was injured in the attempted arson attack and little damage was visible on the outside of the building, said police.
The original 1897 synagogue has been rebuilt once before after the Nazis burned it to the ground during the Kristallnacht pogrom in November 1938.
Meanwhile, a rabbi in Frankfurt am Main received a phone call from a man who threatened to kill 30 Jews in the city if his family in Gaza was harmed.
Dieter Graumann, president of the Central Council of Jews in Germany told the Frankfurter Rundschau on Tuesday that the rabbi received the call last Friday from a Palestinian man.
Graumann said the Jewish community was taking the threat seriously.
And anti-Jewish feelings also seems to be increasing online, a leading researcher into anti-Semitism in Germany said on Tuesday.
Monika Schwarz-Friesel, who is leading a research project at Berlin’s Technical University into anti-Semitism on the internet, said there had been a “massive flood” of anti-Semitic comments.
The professor said anti-Jewish comments were "falling back on old stereotypes," with phrases such as “usurer”, “child murderer” and “global conspiracy” being used again in reference to Jewish people.
In an earlier project, Schwarz-Friesel and a US historian examined 14,000 letters sent to the Israeli embassy in Berlin and to the Central Council of Jews in Germany.
“Hatred of Israel unites writers of all classes,” she said. “Three percent of letters were anonymous and came from the far-right scene.”
Her current project, however, will focus on anti-Jewish forms of communication on social media, online comment areas, chats and forums. "The internet has become the primary distribution medium for the new anti-Semitism,” the TU said in a statement on Monday.
Meanwhile, the left-leaning Linke party has warned about far-right violence against Germany's Muslim population.
On Tuesday, the German press reported figures showing a sharp rise in the number of violent attacks on mosques since 2011.
The figure, which has jumped up by 50 percent in the past three years, had remained constant in the ten years between 2001 and 2011, the Neue Osnabrücker Zeitung said on Tuesday.
An average of 22 attacks on mosques per year were registered in the decade after 2001, whereas that number jumped up to 35 in 2012 and 36 in 2013, the paper said.
The figures were given in a government reply to a question posed by the Linke party.