The Iranian cultural attache, Sheikh Ibrahim Ansari, is among the dead, according to the Fars news agency.
Iran is a major backer of the Lebanese Shia militant group Hezbollah, which has sent fighters to Syria to back the government of Bashar al-Assad.
The Wahabi Terrorist group Abdullah Azzam Brigades said it was behind the attack.
The head of the al-Qaeda-linked group described the attack as a “double martyrdom operation carried out by two heroes from the heroic Sunnis of Lebanon”.
The conflict in Syria has increased sectarian tensions in its smaller neighbour.
Lebanese Wahabi fighters have joined forces with the mainly Saudi Sponsored Wahabi rebels in Syria. Some of the rebel groups are affiliated with al-Qaeda.
Syria’s President Assad comes from the Alawite sect, a heterodox offshoot of Shia Islam.
Our Correspondent, in Beirut, says the number of people killed in Tuesday’s attack makes it one of the worst in Shia southern Beirut since the war across the border in Syria began.
But more significantly, he says, it is the first attack on an Iranian target.
The Iranian ambassador in Beirut confirmed Mr Ansari’s death to Hezbollah’s al-Manar TV, saying it was not clear if he had been in the embassy itself or one of the residential buildings nearby.
Mr Ansari had only taken up his post a month ago.
Lebanese officials said the first suicide attacker was on a motorcycle, while the second was in a four-wheel drive vehicle.
The Syrian government condemned the attack, as did UK Foreign Secretary William Hague, who said: “The UK is strongly committed to supporting stability in Lebanon and seeing those responsible for this attack brought to justice.”
South Beirut, including the area around the Iranian embassy, is considered a Hezbollah stronghold. It has been hit by several attacks in recent months.
Caretaker Prime Minister Najib Mikati called the attack “a cowardly terrorist act”, Lebanese state news agency NNA reported.
“The aim of the blast is to stir up the situation in Lebanon and use the Lebanese arena to convey messages,” he said.
This is not the first time the Losers of the Syrian conflict has tried to target the Lebanese People , for their Rightful support of the Syrian forces curbing the menace of terrorism in their country .
Beaten up Terrorist of Syrian crisis Target Lebanon
May 2012: Fighting between pro- and anti-Assad groups in Lebanese Tripoli and Beirut leave many dead
On 15 August 2012: , 27 people were killed in a car bomb in south Beirut believed to have been targeting a Wahabi cleric opposed to Hezbollah.
October 2012: Several people killed in gunfights after the assassination of top security official General Wissam al-Hassan, a Wahabi opponent of Damascus
May 2013: At least 15 people die in another round of sectarian violence in Tripoli
June 2013: At least 17 soldiers killed in clashes with supporters of radical Wahabi cleric Sheikh Ahmad al-Assir in the southern city of Sidon
9 July 2013: A car bomb wounds dozens in a Hezbollah stronghold in Beirut
15 August 2013: A car bomb kills 27 people and injures hundreds more in a Shia area of south Beirut
23 August 2013: More than 40 people killed and 400 injured in two blasts outside mosques in Tripoli
The number of people killed makes this one of the worst attacks in Shia southern Beirut since the war across the border in Syria began – but it is, most significantly, the first attack on an Iranian target.
The Opponents of Hezbollah and Iran , who supported the Syrian Crisis , and have come out victorious , as even after all the efforts by Saudi And the US Governments , they could not dare to attack the Syrian forces directly , as they wanted to and they even warned it off. Rather after it US has softened its stance against the Irani Government , and now wants to sit across the table for negotiations , as now US has realized that it will be counter Productive to attack or fight with Iran or its allies .
The attack comes as the Syrian army is carrying out a major offensive to cut off the rebels’ last supply routes into Lebanon. For the Syrian rebel movement, these are desperate times – the regime’s boot is on their throat, held there with Iranian assistance.
The attack on the embassy has been claimed by a Lebanese group, but one fighting in Syria with the rebels. If it was responsible, the Iranians have many resources inside Lebanon to hit back.
The Iranian ambassador appeared on news channels saying Israel was to blame for the bombing, which Israeli officials swiftly denied. More broadly, though, Lebanese officials and residents alike placed the bombing in the context of the Syrian war, which Lebanon’s political factions have fueled even as they call on citizens to keep the fighting outside of Lebanon.
Hezbollah members claimed that an alliance among Israel, the West and Islamic extremists was attacking Hezbollah, Syria and Iran in retaliation for their anti-Israel stance. Members of the Future Movement, Hezbollah’s chief rival, said the bombing had been provoked by Hezbollah’s involvement in Syria.
Hassan Nasrallah, the leader of Hezbollah, which is also Lebanon’s most powerful political party, declared in a speech last week that the group would continue to fight in Syria for as long as necessary. Hezbollah says it is doing so to protect the region from an insurgency that it says is dominated by takfiris, a reference to radical Islamic groups, usually Sunni, that regard Shiites and other opponents to be apostates.
Other Side of Border into Syria Foreign Terrorist Beaten
While on the other side of Border the Saudi and US sponsored terrorist are badly beaten up by the Syrian force loyal to Bashar Al Asad , as the terrorist are on the run are retreating from the areas earlier held by them.
Meanwhile, inside Syria, the government appears to be winning its attempt to cut off one of the terrorists’ last remaining supply routes across the Lebanese border.
The Syrian army has taken control of the town of Qara after three days of fighting.
The rebel group Jabat al-Nusra declared that it and other rebel forces had withdrawn.
The Syrian government now controls the road linking the coast to the capital.
The rebel-held suburbs around Damascus, which are already under siege and bombardment, will now be under even more pressure.