National Security Adviser Steven Hadley and White House Deputy Chief of Staff Joe Hagin listened to the concerns of Cindy Sheehan and five or six other mothers in a meeting on Saturday that lasted about 45 minutes, White House spokesman Trent Duffy said.
Duffy said Sheehan told the two officials she appreciated the meeting.
"I want to ask the president, why did you kill my son? What did my son die for?" Sheehan, 48, of Vacaville, California, told reporters before meeting with Hadley and Hagin.
Sheehan blames Bush for the death of her son, US Army Specialist Casey Sheehan, 24, killed on 4 April 2004, in Sadr City, Baghdad.
The protest coincided with release of a Newsweek poll that said 61% of Americans disapproved of the way Bush was handling the situation in Iraq. The poll came after more than two dozen Americans were killed in the past week in Iraq.
Poll rating falls
Newsweek said it was Bush's lowest rating on Iraq and the first time it had dropped below 40% in its poll.
Pentagon officials have said maintaining public support for the war is key to the troops' morale.
Protesters marched on the
roadside towards the ranch
The group of protesters, including US veterans from the Iraq and Vietnam wars, were loud yet peaceful, and McLennan County sheriff's deputies, trying to avoid arrests, stopped them on a road about 8km from Bush's ranch on a hot August day.
"W killed her son! W killed her son!" the crowd shouted, referring to Bush by his middle initial. They also shouted "bring the troops home now" and held up signs with slogans such as "impeach the chicken-hawk-in-chief".
The protesters, many who came from a peace rally in Dallas, drove towards the ranch in a school bus painted red, white and blue. It was stopped at a police checkpoint, and the protesters got out and walked.
Police allowed the group to walk on the side of the road for under a kilometre but stopped them when some in the group walked on the street.
After some protesters left, a small group led by Sheehan vowed to stage a vigil on the side of the road until someone representing the White House came out to talk.
White House officials were aware of the protest, and Duffy said before the meeting: "We mourn the loss of every life and Americans deeply appreciate those who have made the supreme sacrifice. The way to honour that sacrifice is to complete the mission so that their lives were not lost in vain."
As Americans question his Iraq policy, Bush crowed about the strength of the US economy on Saturday and credited his hotly debated tax cuts for the growth.
President Bush is on a 33-day
The president was upbeat in his weekly radio address a day after the Labour Department reported the US economy added 207,000 jobs last month, a stronger-than-expected gain.
"Recent economic reports show that our economy is growing faster than any other major industrialised nation," he said from his ranch.
Bush renewed his call for making permanent the tax cuts he pushed through Congress in his first term. Democrats think the tax cuts have done little more than drain the US budget, and even some Republicans doubt the wisdom of extending them.
"The tax relief stimulated economic vitality and growth and it has helped increase revenues to the Treasury," Bush said, adding later: "We need to make the tax relief permanent."
Bush spoke at the end of the first week of his 33-day working vacation.