Bush made the remarks in a televised address late last night from the Oval Office.
He said work in Iraq has been "more difficult than we expected" but urged Americans not to "give in to despair."
Bush said the recent parliamentary elections in Iraq will not end the violence there, but he added that they mark the beginning of a constitutional democracy in the heart of the Middle East.
The speech was Bush's fifth on Iraq in the course of nearly three weeks. In those addresses, Bush has admitted setbacks in Iraq and outlined a strategy he says will enable the Iraqi people to establish a stable political system and a strong defense capable of putting down the insurgency.
Coalition Images Of The Voting
The Multinational Force in Iraq on December 15, 2005, released official images of the voting in the legislative elections. To view a slideshow of their photographs, click on the image.
To see RFE/RL's special webpage about the election, click here.