Quoted from The Power Broker by Robert A. Caro below mentions the coinage of “kike.”

For a while the motives which impelled the rich Jews to help the poor Jews was certainly in part manifestion of Zedakah, the religious principle of charity, historians have also found other motives. They have found that many German Jews —solid, respectable, Americanized—were embarassed by the gruff, uncouth, shaggy-bearded, conspicuosly un-Americanized newcommers. “Those people,” the Germans felt, were loud, pushy, aggressive—”The dregs of Europe.” They spoke of them in terms other applied to the Yellow Peril, the German-Jewish press lamenting the “Un-American ways” of the “wild Asiatics”. The German-Jews even coined a word for their coreligionists, a word based on the fact that many Russian names end in “ki.” The word was “kikes.” Yet, despite their efforts to make clear the difference between themselves and the newcomers, they realized that non-Jews were lumping them all together, taking the behavior of the newcomers as the sterotype by which they thought of all Jews.