The incident occurred on Wednesday when a bus carrying Shia Muslims from Syria to Iraq came under a bombing attack near Khamsat Kilo, west of the provincial capital Ramadi.
At least 10 others, including four Lebanese and six Iranians, were also injured in the terrorist attack.
On May 22, militants linked to the Syrian opposition kidnapped 13 Lebanese pilgrims in the Syrian city of Aleppo while they were returning to Lebanon from a pilgrimage in Iran.
Crisis-hit Syria has been the scene of killings, explosions, and abductions over the past year.
Foreign-backed armed groups carry out terrorist operations in the country since the unrest began in March 2011.
The Syrian government says ''outlaws, saboteurs and armed terrorist groups'' are behind the unrest, adding that the violence is being orchestrated from abroad.