A number of Lebanese officials arrived at the scene of the blast, including Hezbollah MP Ali Meqdad who said “no matter how much they try, they will fail.”
Ambulances also rushed to the scene of the explosion that sent black smoke plumes into the sky while hospitals in the area appealed for blood.
At least six bodies lay on the street leading to the embassy as firefighters extinguished flames from vehicles. Debris littered the site of the explosion.
Three buildings around the embassy were damaged as well as other buildings in the area.
“I was waiting at the traffic sign on the street parallel to the Iranian embassy when I heard a loud explosion,” said a motorist, who refused to be identified.
“I was terrified. I saw black smoke, but I decided to continue my trip to Shweifat [southeast of Beirut],” she added.
Two devastating explosions had ripped through the southern suburbs of Beirut in July and August, killing dozens of people and wounding scores more.
Hezbollah is deeply involved in the Syrian war with fighters fighting alongside forces loyal to Syrian President Bashar Assad against rebel forces.
Hezbollah chief Sayyed Hasan Nasrallah accused Islamist Takfiri militants of being behind the car bombings that targeted the Bir al-Abed and Ruwaiss neighborhoods in the southern suburbs of Beirut.