In a statement issued in Cairo and translated by the intelligence monitoring group SITE, al-Qaida said bin Laden's death will turn U.S. happiness over the raid and killing "into sorrow and their blood will be mixed with their tears," CNN reported.
Bin Laden was killed in a U.S. Navy SEAL raid on his Abbottabad, Pakistan, compound early Monday, shot in the head and chest. His body was then buried at sea.
The al-Qaida statement praised bin Laden and urged Pakistanis, already upset about U.S. incursions into their territory, to "rise up and revolt" and cursed Americans "inside and outside their countries." The statement also promised jihad will continue on "the path walked upon by our leaders and on top of them … without hesitation or reluctance."
CNN also quoted a Pakistani intelligence official as saying dozens of people in Abbottabad had been arrested for aiding bin Laden. It was unclear whether those arrested were associated with al-Qaida, CNN said.
White House spokesman Jay Carney said the al-Qaida statement just acknowledged the obvious.
"We're being extremely vigilant. You can ask questions of the Department of Homeland Security as well, but the -- we're quite aware of the potential for activity and are highly vigilant on that matter for that reason," Carney told reporters en route to Indianapolis, where President Obama is making an appearance at a transmission plant before heading to Fort Campbell, Ky.
"One of the things we saw I think last night was the notice that DHS put out with regard to the information collected about the consideration at least of a terrorist plot against American railways back in February of 2010. The fact that the world's most wanted terrorist might have been considering further terror plots against the United States is not a surprise, but it reminds us, of course, that we need to remain ever vigilant."
The al-Qaida statement comes as U.S. intelligence experts are combing material seized from bin Laden's compound during the raid, and as legal experts debate whether the raid violated any laws.
Officials said the CIA had bin Laden's compound under surveillance for months before Navy SEALs killed him in Monday's 1 a.m. (local time) assault.
U.S. spies watched and photographed residents and visitors from a rented house nearby in what The Washington Post called "one of the most delicate human intelligence-gathering missions in recent CIA history."
The mission involved Pakistani informants and other sources to help assemble a "pattern of life" portrait of the occupants and daily activities at the bin Laden compound, the officials said.
The effort was so extensive and costly, the CIA asked Congress in December for permission to reallocate tens of millions of dollars to fund it, U.S. officials told the Post.
The material seized from the compound indicated that though bin Laden was out of sight he was still taking an active interest in terror planning.
A notebook from February 2010 taken from the compound indicated bin Laden and al-Qaida considered threatening the U.S. train network on Christmas, New Year's Day and the day of the State of the Union address, officials told The New York Times.
There was no evidence of a specific plot, but the U.S. Department of Homeland Security Thursday issued a bulletin alerting law enforcement officials of the possibility, the Times and The Wall Street Journal reported.
An Obama administration official said documents referring to attacks on railroads were among the first to be translated from Arabic and analyzed.
Earlier this week, Attorney General Eric Holder told Congress the bin Laden operation was lawful, with the administration relying on the Authorization to Use Military force Act of 2001, which authorizes "all necessary and appropriate force" to bring those involved in the Sept. 11, 2001, terror attacks to justice.
But law Professor Kenneth Anderson told ABC the legal issues have been muddled by the administration's evolving accounts of what actually happened. Anderson allowed that bin Laden was a "legal target" for lethal force. Less clear, he said, is whether bin Laden was armed or asked to surrender.