The court said in a written verdict on Sunday that Sufuwan Mahmoud Yousri was the getaway driver for the Palestinian gunman who opened fire at a car belonging to the Temporary International Presence in Hebron (TIPH) in March 2002 near Hebron.
Two of the monitors, a Swiss woman and a Turkish man, were killed in the attack.
Hussein Ozar Salam, a Turkish observer who was wounded, said in an interview after the shooting that a gunman wearing a Palestinian police uniform opened fire at close range at the vehicle which was clearly marked with TIPH logos.
"The accused never expressed any remorse," the court said in its verdict. It said that Yousri acted on behalf of the Islamic Jihad group.
Palestinian officials denied at the time that a Palestinian had been involved in the incident.
TIPH has been critical of the behaviour of the 400 Jewish settlers who live in Hebron.
Israeli soldiers killed the fighter suspected of pulling the trigger in the attack on the TIPH car during an attempt to arrest him at a roadblock near Hebron last year.
The TIPH was established by the international community following the killing of 29 Palestinian worshippers by an Israeli settler in Hebron on in February 1994.
The group - which is supported by Denmark, Italy, Norway, Sweden, Switzerland and Turkey, and coordinated by Norway - currently monitors arrangements in Hebron which under a 1997 peace agreement is divided between Israeli and Palestinian rule.
The group has been critical of the behaviour of the 400 Jewish settlers who live in Hebron.