(Two quotes I received in an email from Henry Benjamin Winkler, who publishes an email-newsletter titled “The Hebrew Wink”.)
10 days before his assassination, at the annual convention of the Rabbinical Assembly [*], Dr. King said:
“The response of some of the so-called young militants does not represent the position of the vast majority of Negroes. There are some who are color-consumed and they see a kind of mystique in blackness or in being colored, and anything non-colored is condemned. We do not follow that course…. Peace for Israel means security, and we must stand with all our might to protect her right to exist, its territorial integrity and the right to use whatever sea lanes it needs. Israel is one of the great outposts of democracy in the world, and a marvelous example of what can be done, how desert land can be transformed into an oasis of brotherhood and democracy. Peace for Israel means security, and that security must be a reality.”
Source: I. L. Kenen, Israel’s Defense Line, Prometheus Books, Buffalo, NY: 1981, p. 266 
Dr. King on Anti-Zionism:
When approached by a student who attacked Zionism, Dr. King responded: “When people criticize Zionists, they mean Jews. You’re talking anti-Semitism.”
Source: Seymour Martin Lipset, “The Socialism of Fools—The Left, the Jews and Israel,” Encounter, (December 1969), p. 24 
[personal note: I like the quote; not the title of the article it comes from]
[*] The Rabbinical Assembly is the membership organization for rabbis associated with the Conservative/Masorti branch of Judaism.
In all fairness, after posting the above quotations, a friend sent me a link to an article that questions the validity of the quotes and their sources. For those who want to examine it:
My own response to this was that while I respected the reasoning involved, I didn’t see where the authors applied the same rigor to questioning the validity of statements made against Israel as they did to statements made in Israel’s favor.
Another article about MLK and Israel from “Jewish Ideas Daily”: