Perhaps the most prominent site was news site Alef, under the title "What group has been the biggest criminals in the history of mankind?"
The article includes the most grotesque artwork of Jews as murderers, both medieval and modern, including this one that they took from an antisemitic Arabic Facebook page:
It goes through many countries and lists every Jewish blood libel. It claims that the reason Jews were expelled from Spain was because of their habits of murdering Christian babies.
The article even reproduces a cover of Der Sturmer from 1939 showing the Nazi paper accusing Jews of ritual murder as evidence that it must be true!
(The article also include a video of a 1989 Oprah interview of a mentally ill woman named "Rachel" who made bizarre claims that her Jewish family was part of a cult that sacrificed babies and who raped her on a Torah scroll in a synagogue, among other things. I spent a little time researching this, and I don't want to have that story hijack this post, but from what I can gather all her "memories" had been prompted by a highly unethical therapist when the idea of reconstructing repressed memories was very popular. None of her stories have ever been corroborated by anyone she knows. Interestingly, she has become a prominent if controversial advocate against sexual abuse of children since then.)
Beyond that, the article claims that rabbis mix human blood with wine and place it on the lips of the infant boy during circumcision. It claims that the Talmud says "Anyone who kills a non-Jew, his reward is in heaven."
Other news sites that reproduced the article, verbatim, include Mashregh News, Asredena, Harfeakhar, Khabarist, Khabarkhoon, Habbe, and Ghatreh. From there it has spread to blogs and other secondary sites.
Most of the comments are virulently antisemitic as well.
Nothing gets published in Iranian websites without permission of the government, and this is a clear and conscious decision to promote Jew-hatred in Iran. Antisemitism is official Iranian policy.
Westerners who had guided tours of Iran and then claim that Iran has no antisemitism. like Roger Cohen, are once again shown to be useful idiots.
(h/t Gidon Shaviv and @RZimmt)