The convicted defendants - mostly Jordanians or Jordanians of Palestinian descent - were sentenced on Sunday to prison terms ranging from one and a half years to three years after being found guilty of conspiring in 2004 to carry out the embassy attacks.
The 12 defendants, who did not enter pleas, were also accused of planning other attacks, including against a hotel popular with Israeli tourists in the northern city of Irbid; the home of a cultural festival director and an American troupe performing at the annual event.
Wearing prison uniforms, the defendants stood behind bars in the courtroom dock to hear the handing down of the guilty verdicts, which can be appealed. Another four defendants were acquitted for insufficient evidence.
As the sentences were handed down, the defendants started hailing the fourth anniversary of the terror attacks on the United States.
"Our brothers have made America cry on this day," one of the defendants shouted from the chicken wire-covered cage holding them in the courtroom.
"This is the day that showed how vulnerable America is."
Group mastermind Abed Shihadeh al-Tahawi described the trial and sentencing as "a plot hatched against us to satisfy America and Israel."
Many terror convicts accuse the government of Jordan, which signed a 1994 peace deal with Israel, of exaggerating terror plots against the kingdom to garner US support.
US vessels in the port of Aqaba
recently came under attack
"This verdict will not dissuade us from pursuing the path of jihad," he shouted.
Al-Tahawi, 50, and two others were sentenced to three years' jail for leading the conspiracy, raising funds, recruiting fighters, mapping out plans and sending men for training in Yemen and Iraq.
Two others were given two-year terms and the remaining seven sentenced to one and a half years.
The prosecution did not say how the defendants planned the attacks. The plot was uncovered and foiled when the defendants were detained in August and September last year.
Al-Tahawi was accused of pursuing the takfiri ideology, which is bent on killing anybody considered an infidel. He allegedly has recruited accomplices while preaching in mosques in Irbid, 80km north of Amman.
During the trial that opened in March, the defendants repeatedly praised Abu-Musab al-Zarqawi, the Jordanian-born leader of al-Qaida in Iraq. But the chargesheet did not directly link the defendants to al-Zarqawi or any other known group.
Separately, the military court upheld a June 2004 guilty verdict against Jordanian Ahmad Mahmoud al-Riyati, described as an al-Qaida terror cell leader, who was jailed for seven and a half years for plotting terror attacks against unspecified US and Israeli interests here.
The verdict came nine months after an appeals court asked for a retrial citing "technical faults" in last year's trial.
"This verdict will not dissuade us from pursuing the path of jihad"
Group mastermind Abed Shihadeh al-Tahawi
Al-Riyati began plotting attacks in Jordan as early as August 2001 in mutual agreement between Osama bin Ladin's al-Qaida network and another group, Ansar al-Islam, the court heard.
His targets also included Western tourists and top Jordanian intelligence officials. Details of the plots were not revealed. Al-Riyati has denied the charges.
Jordan has been battling hardliners for several years and regularly sentences "militants" either at large or in custody to heavy prison sentences.