The US military denied a family of six was killed, saying it launched four strikes against safe houses used by Zarqawi's fighters.
"Intelligence sources indicate a known Zarqawi propagandist is passing false reports to the media," it said in a statement.
Reuters television footage showed men chanting "There is no God but Allah!" as they carried the body of the father of the family of six.
"Is this the gift that (interim Iraqi Prime Minister) Iyad Allawi is giving to the people of Fallujah?" Asked one man, pointing to the small bodies of two of the children lying in the trunk of a car. "Every day they strike Fallujah."
At least eight civilians were killed and 11 US soldiers received injuries in clashes in Samarra, a northern town the US military said it had pacified following an offensive earlier this month.
Two car bombs killed a child and also wounded a civilian translator in the centre of the town, the US military said. A police official said eight civilians had been killed and 12 wounded in clashes.
Care International, an aid agency working in Iraq on health and water projects, suspended operations after its British-Iraqi manager in Iraq, Margaret Hassan, was abducted and said it might pull out of the country altogether.
"At the moment we have suspended operations, and we will continue to pull out of the country unless we can resolve this issue," Care International Chief Geoffrey Dennis told BBC radio.
The US military says its almost nightly strikes on Fallujah are carefully targeted at fighters led by Jordanian militant Zarqawi, who it says is holed up in the city. But the residents say they know nothing about Zarqawi - some even doubt his existence - and that the US raids kill civilians.
Allawi has warned Fallujah's residents to hand over Zarqawi's followers or face military action. He has said he remains open to talks, but Western diplomats in Baghdad say an offensive against the town of 300,000 is becoming increasingly likely.
In other violence, an adviser to Allawi's political party was killed in a drive-by shooting in Baghdad on Wednesday, an Interior Ministry spokesman said.
British Prime Minister Tony Blair told parliament he expected an upsurge of violence in Iraq before the elections.
Blair said he had not decided yet on a US request to shift British troops to more dangerous parts of the country to free up US forces for other action.
Some accuse him of having already agreed to do so to help President George W. Bush before the November 2 US presidential elections, in which Iraq has been a major campaign issue.
Iraq would urge other countries to help it improve security and prepare for elections at an international conference in Egypt next month, officials said.
The United Nations, European Union, Arab League, Organisation of Islamic Conference, Group of Eight top industrialised countries and China are among those planning to send representatives.