After meeting Jordan's King Abd Allah in Washington on Thursday, Bush told journalists: "I told him I was sorry for the humiliation suffered by the Iraqi prisoners and the humiliation suffered by their families".
"I told him I was equally sorry that people that seen those pictures didn't understand the true nature and heart of America. I assured him that Americans like me didn't appreciate what we saw."
Bush's remarks echoed apologies offered in recent days only by his top aides, including his national security adviser, Condoleezza Rice.
Many Arabs have expressed anger and disappointment that Bush did not apologise for the prisoner abuse scandal during his interview on two Arabic-language television channels on Wednesday.
That anger was fuelled again on Thursday with the publication of more photos.
One picture shows a US soldier with a prisoner on a dog leash, while another shows a soldier giving a thumbs-up sign next to what seems to be a dead body.
Bush told reporters the abuse was "a stain on our country's honour."
He also defended Donald Rumsfeld, the US defence secretary whom many Democrats, including the party's leader in the House of Representatives, say should resign over the affair.
Bush stood by his embattled defence secretary, although aides said on Wednesday he had privately expressed annoyance over the Pentagon chief's handling of the scandal.
House Democratic leader Nancy Pelosi accused Rumsfeld of being "in denial about Iraq," and said US soldiers "are suffering great casualties and injuries, and American taxpayers are paying an enormous price" because Rumsfeld "has done a poor job as secretary of defence".
The abuse is "a stain on our country's honour."
US president George Bush
"Secretary Rumsfeld must resign," she said. Pelosi said Rumsfeld "must be held responsible for any cover-up" of the abuses that came to light last week with televised photographs showing sexual humiliation of Iraqi prisoners in a jail outside Baghdad.
Some top House Republicans dismissed the resignation calls, and many lawmakers said it was too early to fix blame for a scandal that most acknowledged posed a major setback to US efforts to stabilise Iraq.