Jewish people are not flawless paragons. To portray them as such is to deify and other them, striping them off their humanity. They are human beings, flawed in all the same ways the rest of humanity is flawed. That includes, in many but not all, racism. It's not antisemitic to say that some are racist. They're human, and racism is a very human trait. You're the antisemite. You deny them the flaws of being human, and other them as universally perfect.