Bush was flown by helicopter to northern Israel after touring Jerusalem's Yad Vashem memorial to the six million Jews killed in the Nazi Holocaust.
Wearing a black skullcap, he walked sombrely past photographs of victims. At a ceremony in the stark Hall of Remembrance, Bush rekindled an eternal flame and laid a wreath on a stone slab under which ashes of victims of six death camps are buried.
"I would hope if many people in the world would come to this place, it would be a sobering reminder that evil exists and a call that when we find evil, we must resist it," Bush said at the memorial.
"I guess I came away with this impression, that I was most impressed that people in the face of horror and evil would not forsake their God - that in the face of unspeakable crimes against humanity, brave souls, young and old, stood strong for what they believe."
In his talks with Olmert and Abbas, both politically weak leaders, Bush sought to create momentum towards establishing a Palestinian state, after a November summit in Annapolis, Maryland intended to jump-start peace talks.
The White House said he was likely to return to the region before his term ends.
Bush is scheduled to leave for Kuwait later on Friday followed by visits to Arab allies in Bahrain, the United Arab Emirates, Saudi Arabia, and Egypt.
He will ask them to support his Israeli-Palestinian peacemaking efforts and to help curb the growing regional influence of Iran.
"They can do a lot of things," Bush said.
Arab allies could provide diplomatic support to Abbas, give him greater financial support, and "begin to reach out to Israel and indicate in a tangible way that they support this diplomatic process", he said.
