"But we have one condition: this discussion should be carried out ... with the will and consent of the various Lebanese factions," he added.
In the wake of the blast, Hezbollah has come under unprecedented public criticism and its role in Lebanese politics under intense scrutiny.
The military also ordered civilians in nearby communities to shelter in place and blocked roads near the border.
Such incidents are rare in Iran, though a series of bombings targeted several Iranian nuclear scientists between 2010-2012.
"I categorically deny" such rumours, Hezbollah chief Nasrallah said in a televised speech.
Iran said Hezbollah had a "key role in fighting Daesh's terrorism in the region," using the Arabic acronym for the Islamic State group.
The United States and Israel welcomed Germany's move against the group, which is rooted in Lebanon’s Shiite community and has close ties to Iran.
It was a new round of penalties on Iran and its overseas connections by Washington following US President Donald Trump's announcement of withdrawing from the landmark Iran nuclear deal last week.
The leader of Shi'ite Hezbollah, Sayyed Hassan Nasrallah had called the result a "a very big political, parliamentary and moral victory for the choice of resistance".
Hezbollah leader Hassan Nasrallah called the vote a great political and moral victory for the resistance option that protects the sovereignty of the country.