Jordan is "not afraid" and will not be cowed into changing its policies by the bombs which killed 56 in Amman hotels, King Abdullah has told the nation.
"These acts will not make us... retreat from our role in fighting terror in all its forms," said the leader of a state which is a key US ally.
He also made a call for a global strategy against terrorism.
Supporters of the king have rallied to condemn "Jordan's 9/11" which has been claimed by the Al-Qaeda in Iraq group.
Nearly 100 people, mostly Jordanians, were injured in the three blasts, at the Grand Hyatt, Days Inn and Radisson SAS hotels. The blast at the latter caused carnage at a wedding reception.
Most of the dead are Jordanians but a number of other Arabs, two Chinese, one American and an Indonesian are also known to have died.
King Abdullah told a security meeting that "the war against terrorists must strike all those who justify... their actions or support their destructive beliefs".
'Burn in hell'
At least several hundred people marched through Amman to denounce the bombers and show loyalty to King Abdullah.
"Burn in hell, Abu Musab al-Zarqawi," they chanted, referring to the Jordanian-born militant believed to lead al-Qaeda in Iraq.
The claim from al-Qaeda in Iraq appeared on a website generally used to post such announcements.
It said the hotels were targeted because they had become favourites with "American and Israeli intelligence and other Western European governments".
Jordan has become a base for Westerners who fly in and out of Iraq for work and has long been regarded as a prime target for attack, correspondents say.
According to Jordanian officials, 56 people died in the attacks along with the three bombers, and 96 were wounded.
DNA tests are being used to identify at least 14 bodies, including those of the bombers.
Two bombers seem to have used devices strapped to their bodies while the third used a car bomb.
The bomb attacks have been condemned "in the strongest terms" at the UN Security Council while US President George W Bush said they were "cowardly attacks on innocent Jordanians and their guests".
UN Secretary General Kofi Annan is due to arrive in Amman on Friday, after delaying a scheduled visit by one day.
Wedding party attacked
In the most deadly attack, hundreds of guests were enjoying a wedding reception at the Radisson SAS when the bomb went off.
The bride and groom each lost a parent and were themselves injured.
"There were a lot of injured people and some dead people," the groom, Ashraf al-Khaled, said.
"I lost my father and my father-in-law on my wedding night."
Security has been tightened around Amman and Jordan's land borders have been closed.
Roadblocks were set up around hotels and embassies, and Prime Minister Adnan Badra ordered all schools and public offices to close on Thursday.
1. Vehicle explodes outside hotel after being stopped at a police checkpoint
2. In the most deadly attack, a bomb destroys a banquet room where a wedding reception was being held. Dozens injured by shrapnel
3. Suicide attacker detonates bomb in hotel bar, just before 2100 local time. Two senior Palestinian officials are among the dead