"Friends say that this young man saw the images of September the 11th, and seeing that evil, he felt called to defend America," Bush said at the dinner.
Bush also said Tillman and his colleagues "do brave and good things without notice."
"We honor with pride and wonder the men and women who carry the flag and the cause of the United States," Bush said in his speech.
However, a week after Tillman died, a top general sent a memo to Gen. John Abizaid, then head of Central Command, warning that it was "highly possible" that Tillman was killed by friendly fire.
The memo made clear that the information should be conveyed to the president. However, the White House has maintained the President didn't received the warning.
Rep. Henry Waxman, D-Calif., chairman of the House Oversight Committee, and Rep. Tom Davis, R-Va., the committee's top-ranking Republican, plan to interview or depose five former White House officials including Scott McClellan, a former White House press secretary; Dan Bartlett, the recently resigned White House counselor and communications czar; Michael Gerson, a former speechwriter; John Currin, a former fact-checker on the speechwriting team; and Taylor Gross, another former spokesman.
The committee plans a second hearing on Tillman's death for Aug. 1, this time to probe what senior Pentagon officials knew and when. Former Defense Secretary Donald Rumsfeld; Richard Myers, the former chairman of the Joint Chiefs of Staff; and Abizaid were among those the committee has invited to appear.
With files from the Associated Press.