He also vowed – unlike Sanders – to keep the Israeli embassy in Jerusalem and voiced his opposition to the BDS movement.
The speakers take part in the three-day conference, speaking on the Monday morning general session at Washington.
"The people of Selma will struggle for the soul of the nation," Bloomberg told his audience, as a number of those in attendance silently stood and turned their backs.
Vice President Mike Pence will be the keynote speaker this year. Secretary of State Mike Pompeo and US Ambassador to Israel, David Friedman, will address the conference as well.
Campaign literature put out before the event said that Bloomberg, who along with Bernie Sanders is Jewish, has been “a champion for Israel."
"What I happen to believe is that right now – sadly, tragically, in Israel, through Bibi Netanyahu – you have a reactionary racist who is now running that country," Sanders said.
Bloomberg's main competition in Israel is most likely the other Jewish candidate, current Democratic frontrunner Bernie Sanders, who in 2016 won 60% of the vote, compared to Hillary Clinton's 40%.
The action was first reported by the Los Angeles Times.
In the past week, two Bloomberg offices in Ohio were defaced with the spray-painted words “oligarch.” In Michigan, offices were vandalized with “corporate pig” and “Eat the rich.”
After three years broadcasting from Modi'in, Public Broadcasting broadcast the 6am news from Jerusalem on Sunday.