The rector of the Abraham Geiger College in Potsdam, an academic seminary for rabbis, warned his students against wearing the kippah, or yarmulke, the traditional Jewish head covering, after a rabbi was beaten up in broad daylight earlier this week in Berlin.
"If you are no longer seen as a Jewish person, you are safer," Walter Homolka told the Berliner Morgenpost daily.
Daniel Alter, 53, was attacked by four youths of Arab background in front of his 6-year-old young daughter after collecting her from a piano lesson on Tuesday. One youth smashed the rabbi in the face several times after asking him if he was Jewish, apparently because he was wearing a traditional head covering, police said. They also shouted religious insults.
The assailants fled, but not before aiming death threats at the young girl, according to authorities, who have launched an investigation into the Tuesday attack.
The rabbi needed hospital treatment to his face.
Police have launched an investigation but the alleged assailants are still at large.
German media reported that the rabbi’s beating sparked fury in the country with some Jewish groups saying they feared a rise in anti-Semitic behaviour. Over the last months, the Jewish community was already up in arms over a court ruling in western Germany that outlaws religious circumcision.
Germany’s Central Council of Muslims condemned this week’s attack.
Alter told the Bild daily newspaper that he was shocked at the shameless way his attackers had assaulted him in front of his daughter. "I am not sure whether we will be able to walk the streets of Berlin without fear again."
He was made a rabbi in Dresden in 2006. He and two others were the first to be ordained in Germany since 1942, when the College of Jewish Studies in Berlin was destroyed by the Nazi Gestapo secret police.
His father survived Auschwitz concentration camp.
The Central Council of Jews in Germany condemned the attack, saying it showed violent anti-Semitism had again become a serious social problem.
The president of the Central Council called Friday on the country's large Muslim community to do more to combat anti-Semitism. "I would be pleased if (Muslim) associations would finally deal decisively with anti-Semitism in their own ranks," Dieter Graumann told the Berliner Zeitung daily.
The Central Council of Muslims said Muslims were shocked by such incidents.
"At this time, Jews and Muslims must stand together and make clear: violence of any color has no place with us," said the Council's chairman Aiman Mazyek who expressed his "deep disgust" on behalf of the community, in a statement.
"Words and sympathy are nice and meant honestly, but deeds would also count," said Dieter Graumann.
Berlin mayor Klaus Wowereit said the incident was "an attack on the peaceful co-existence of all people in the capital".
Germany's official Jewish population has grown more than 10-fold in the last 20 years, largely thanks to an influx of Jews from the former Soviet Union, but anti-Semitic attacks are common place and policemen guard synagogues round the clock.
The Abraham Geiger College, which currently trains 28 rabbis, said it had boosted security around the building as a result of the attack and was checking mail.
"We have also given guidelines to our students on how to behave so that they do not become victims of such attacks," the rector said.
"We have advised them not to wear their skullcaps on the street, but to choose something inconspicuous to cover their head with," Walter Homolka added.
He urged the police and intelligence services to deal with violent Muslims. "It would be fatal if we were to see a proxy Middle East war on German streets," he said.
Berlin rabbi Andreas Nachama told AFP that Germany had seen over the past few years "a rising hostility towards Jews due to the conflict in the Middle East."
"Verbal attacks against Jews have increased," said Gideon Joffe, head of the Jewish Community of Berlin, in an interview with local daily Tagesspiegel.
Another Berlin-based rabbi, Walter Rothschild, told German radio: "I have been spat on in broad daylight in (the central Berlin square of) Wittenbergplatz and had slogans linked to the Middle East shouted at me."
The American Jewish Committee called on Germany's parliament to act on a report on anti-Semitism which included recommendations on ways to combat anti-Semitism.
The report also said that anti-Semitism was entrenched in German society, manifesting itself in hate crime as well as in abusive language used by ordinary people.
"German lawmakers should not delay any longer adopting a comprehensive plan to combat anti-Semitism," said Deidre Berger, the AJC's Berlin director.
The attack came amid a fierce row over a ruling by a court in Cologne, western Germany, that circumcision of young boys for religious reasons was tantamount to grievous bodily harm and therefore illegal.
The ruling has prompted fears that religious freedom is being restricted in Germany and has brought Jews and Muslims together in condemning the judgement.
Chancellor Angela Merkel has reportedly said the ruling risks making Germany a "laughing stock" and diplomats admit privately it is "disastrous" for the country's image abroad, given its Nazi past.
Other religious leaders also condemned the attack, with Catholic group Pax Christi saying it was an "attack on Jewish life in Germany."