Security sources said on Fridaythat the car rigged with 400 kilograms (250 pounds) of explosives was found at dawn.
The army, on alert since Tuesday's attack outside the Iranian embassy, had spotted the suspect vehicle earlier, state media said.
Troops gave chase to the car and exchanged fire with the passengers but it got away, the official National News Agency said.
The army eventually found the vehicle abandoned on a road between the villages of Makneh and Yunin with its tires burst, the news agency said.
The identity of the passengers was not immediately known nor was it clear where they had planned to blow up the vehicle.
The incident came as Lebanon marked the 70th anniversary of its independence from French colonial rule.
The 32-month conflict in neighboring Syria has stirred tensions in Lebanon where many Takfiris back the militant groups.
In October, the army defused a car bomb in south Beirut, weeks after it was hit by two bombings.
NTJ/SHI