Bacon rashers were found wrapped round the door handles of a synagogue as congregants arrived for a Shabbat service last weekend.
Police were called to Sinai Synagogue in Leeds on Saturday morning. They also found meat stuffed through the key hole.
Sinai is the main Reform synagogue in Leeds and has around 800 members.
Rabbi Ian Morris said: “In the scheme of things it’s almost verging on the humorous. When people are setting out to target the Jewish community it’s a shame, but on the scale of things people do these days it really does not rate terribly highly.
“I suspect it’s not the act of violent antisemites, it’s probably just yobbos out for some fun. I wish we didn’t have to worry about this stuff.”
Mark Gardner, CST communications director, said: “This was a quite pathetic antisemitic attack. Nevertheless, it was very ugly and disturbing for the congregation to have to experienced this, and it was very important indeed for the police to have taken the matter so seriously.”
A West Yorkshire Police spokeswoman said: “We take such incidents very seriously and scenes of crime officers examined the door and dusted for fingerprints.
“Officers also liaised closely with members of the synagogue. We would like to reassure the Jewish community that incidents such as this are rare. Any witnesses are asked to call West Yorkshire Police on 0845 606 0606.”