Unarmed Hezbollah members were searching vehicles and checking the IDs of drivers at several points along the Hadi Nasrallah highway.
The Lebanese Army also set up separate checkpoints in the area.
The heightened security comes days after a suspected suicide bombing killed four people in the neighborhood of Haret Hreik, where the party enjoys broad support.
Tuesday’s bombing was the fourth deadly blast targeting the southern suburbs. Radical Syrian rebel groups have claimed most of the attacks, describing them as retaliation for Hezbollah’s military role alongside President Bashar Assad’s forces in Syria.