Hassan Nasrallah told Lebanon’s OTV television the attack was linked to the Saudi intelligence services.
The Sunni jihadist group Abdullah Azzam Brigades said it was behind the double suicide bombing which killed 25 people.
Hezbollah and its backer Iran support Syrian President Bashar al-Assad, while Sunni Saudi Arabia backs rebel groups.
In the interview, Hassan Nasrallah said the Abdullah Azzam Brigades, the al-Qaeda-linked group, “has an emir and he is Saudi”.
He said he believed that the group was “linked to the Saudi intelligence services”.
The Hezbollah head added that the blasts near the embassy, which is located in Hezbollah’s stronghold in Beirut, were “linked to Saudi Arabia’s rage against Iran over its failure” in Syria.
Saudi Arabia, which condemned the bombings, has so far made no comments on Hassan Nasrallah’s claim.
Among those who died in the blasts in Beirut on 19 November was Iranian cultural attache Sheikh Ibrahim Ansari. More than 140 people were injured.
The Abdullah Azzam Brigades described the attack as a “double martyrdom operation carried out by two heroes from the heroic Sunnis of Lebanon”.
The bombings were condemned by the United Nations Security Council, and the US described them as “senseless and despicable”.
The conflict in Syria has increased sectarian tensions in its smaller neighbor.
Lebanese Sunni Muslim fighters have joined forces with the mainly Sunni 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.
Suleiman blasts Nasrallah over accusation
President Michel Suleiman blasted Wednesday Hezbollah accusations that Saudi Arabia is behind last month’s twin suicide bombings outside the Iranian Embassy in Lebanon.
Suleiman also called on Hezbollah to withdraw from Syria in light of the assassination that targeted a party commander earlier during the day and which Hezbollah held Israel responsible for.
Suleiman described the assassination of Hezbollah top commander Hajj Hassan al-Laqees as part of an Israeli scheme to fuel sectarian strife in Lebanon.
“This crime is part of an Israeli scheme to fuel sectarian disputes,” said Suleiman as he called on the Lebanese to be wary of such provocative attempts.
“It is not allowed to ruin the historic ties with Saudi Arabia by making accusations against it without any evidence,” Suleiman said in a speech delivered in Jbeil during a conference titled “Dialogue, truth and democracy.”
Former Prime Minister Saad Hariri also condemned Nasrallah’s statements saying the comments were driven by hatred and accused Hezbollah chief of distorting facts.