Contactmusic.com reports that Baruch Marzel, an Israeli politician sent a letter on behalf of the Lehava organisation.
"It is not by chance that you were born Jewish. Your grandmother and her grandmother did not dream that one of their descendants would one day remove the family's future generations from the Jewish people. Assimilation has forever been one of the enemies of the Jewish people," stated the letter.
Marzel added that he has "nothing against Mr DiCaprio, who I have no doubt is a talented actor, Come to your senses, look forward and back too and not only the present. Don't marry Leonardo DiCaprio, don't harm the future generations."
The supermodel, who has been dating DiCaprio since 2005, was forced to deny rumours about her engagement earlier this month after she was spotted wearing a ring on her wedding finger.
