The conservative pundit described Soros this week as a "Jewish boy helping send the Jews to the death camps."
Soros survived the Nazi occupation of Hungary and donates to liberal causes.
ADL National Director Abraham Foxman posted a statement Thursday on its website saying Beck's remarks about Soros' childhood were "inappropriate, offensive and over the top."
Foxman later told Salon.com that he still believes Beck is a strong supporter of Israel and the Jewish people.
A Beck spokesman declined to comment but cited an Oct. 22 letter from Foxman praising Beck as a "friend of Israel." The letter was posted Friday on Beck's website.