Neftali Bennett's defense of Kerry followed attacks by a fellow member of the Bayit Yehudi party for the U.S. diplomat's comments earlier this month about a potential boycott of Israel, the Jerusalem Post reported.
"Kerry is not an anti-Semite, whoever suggested that is flatly wrong," Bennett said at the 40th annual Conference of Presidents of Major American Jewish Organizations in Jerusalem.
"America is our greatest ally, it is our strategic friend," Bennett added.
A boycott of Israel would not be well-meant criticism, he said, but "the new anti-Semitism."
The Conference of Presidents is an umbrella organization for 51 of the largest Jewish groups in the United States.
Kerry mentioned a potential boycott Feb. 1 at the Munich Security Conference as a possible ramification in the event peace talks between Israel and the Palestinians fail.
"You see, for Israel there's an increasing delegitimization campaign that has been building up," Kerry said. "People are very sensitive to it. There are talk of boycotts and other kinds of things. Are we all going to be better with all of that?"