The White House has stressed that President Bush is "deeply sorry" for the abuses by US prison guards in Iraq after he failed to apologise directly.
Speaking on Arabic TV, Mr Bush deplored mistreatment of prisoners and vowed to punish any US troops responsible.
But reports indicate widespread anger among ordinary Arabs that Mr Bush did not make a personal apology.
Meanwhile, new photographs have emerged in the US press apparently showing more abuse of Iraqi detainees.
The photographs, obtained by the Washington Post newspaper, include one of a naked prisoner being led on a leash and another showing a group of naked Iraqis sprawled on top of one another while soldiers stand around them.
The newspaper says it cannot eliminate the possibility that some of the images were staged but Washington Post reporter Christian Davenport has said he believes the pictures are authentic.
Photographs of naked Iraqi prisoners in humiliating poses next to laughing US soldiers have shocked the world.
President Bush condemned any abuse as "abhorrent", but insisted that it did not represent "the America that I know" during interviews on two Arabic television stations.
The interviews were aimed at limiting the damage caused to the US in the Middle East by the abuse scandal but Mr Bush stopped short of apologising.
Rumsfeld under pressure
"The president is sorry for what occurred and the pain that it has caused," Mr Bush's spokesman Scott McClellan said afterwards.
Asked why Mr Bush himself had not apologised, he added: "I'm saying it now for him."
The White House spokesman also pointed out that Mr Bush had not been pressed to apologise by the two TV channels on which he appeared, the Dubai-based al-Arabiya and the US-funded al-Hurra.
The scandal is set to return on Friday when Defence Secretary Donald Rumsfeld is obliged to testify in the Senate abuse of Iraqi prisoners.
Mr Rumsfeld is expected appear for two hours before the Senate Armed Services Committee in open session, and will then hold a closed briefing for the full Senate.
White House aides have let it be known privately that Mr Rumsfeld received a dressing-down from President Bush over his handling of the controversial pictures.
The BBC's Justin Webb reports from Washington that Mr Rumsfeld is under the greatest political pressure of his life and could possibly be forced to resign.
Arabs who watched Mr Bush's interview across the Middle East - many of them having to rely only on a summary in Arabic provided by al-Arabiya - told correspondents they were unconvinced by Mr Bush's position.
Asked how he felt, one Baghdad resident said: "I am going to answer this question with another: how would the Americans feel if this happened to them by Iraqis in America?"
"The Iraqi people do not trust at all American talks, whether it was coming from the president or the lowest-ranking soldier," said another.
In Egypt, normally an ally of the US, the government-owned media mocked the gap between the wartime US rhetoric of liberating Iraq and the abuse of Iraqi prisoners.
The BBC's Paul Wood reports from Cairo that those he spoke to said Mr Bush had not seemed angry enough.
However, former Jordanian information minister Nasser Joudeh said the interviews showed the US had realised that it could not ignore the views of the Arab world.
In the US, the Democratic presidential challenger, Senator John Kerry, said in Los Angeles that the Bush administration's response to the prison scandal had been "slow and inappropriate".
Mr Bush has asked Congress for an extra $25bn to meet military costs in Iraq and Afghanistan.
A White House statement said the contingency fund was needed because of increased demands on American troops in Iraq.
Administration officials had previously said they were not planning to ask for any more money this year.
The BBC's Pentagon correspondent Nick Childs says the about-face is likely to provoke a further political row.