Jesus was crucified as a fulfillment of prophecy, not because of Jews or even Romans. Only God can forgive sin, and it is through Jesus' sacrifice that we are forgiven.

There's also the prohibition of usury between Jews which doesn't apply when a Jew loans money to a non-Jew. The notion seems to be that at various times in Europe affluent Jews loaned money and charged interest. People who could not pay their loans were subject to losing their property. You can bet that would engender quite some bitterness. Turns out that in the early 20th century Germany financed their military through borrowing, and while I don't have a source to confirm this it might be reasonable to imagine some of those wealthy financiers were Jews.