One of the British stars of the Tony-nominated show “Giant” is battling antisemitism in art and in life — and he has a dire warning for New Yorkers. Elliot Levey plays Jewish publisher Tom Maschler opposite John Lithgow’s Roald Dahl in the critically acclaimed Broadway hit, a drama about the famous children’s author’s antisemitism. The show originated in London where Levey lives with his family. ‘Giant’ star Elliot Levey worries about the rising antisemitism in the UK. FilmMagic There, the actor would have to dodge mobs of rabid anti-Israel protesters waving Palestinian flags and keffiyehs every Saturday on his way to the West End theatre where the show was staged. “[There were] thousands calling to globalize the intifada , which means to kill Jews around the world,” Levey, a self-proclaimed “proud Jew,” told The Post. Working on Broadway has been a welcome reprieve. “New York is the safest place for Jews on the planet,” he said.…