Hezbollah leader Hassan Nasrallah offered condolences on Saturday to the victims of Paris attacks and vowed retaliation against Islamic State for the bombings in Beirut earlier in the week.
"People of the region of Arab and Islamic countries who are living under the brutality of ISIS, including Lebanon which suffered a few days ago from it, are the most aware and sympathetic of what hit the French nation last night," Nasrallah said in a televised statement. He was referring to Islamic State.
"We offer our deep condolences, solidarity, sympathy, moral and humanitarian stand to those innocent who are invaded by the barbaric criminal management of ISIS," Nasrallah said.
Islamic State has claimed responsibility for Friday's attacks, which killed 129 people in Paris.
In the past two weeks, there have been other major Islamic State-claimed attacks. Two explosions in suicide attacks in a Shi'ite Muslim district of southern Beirut in Lebanon killed 43, and 224 died when a Russian aircraft crashed in Egypt's Sinai Peninsula.
Islamic State said in a statement posted online by its supporters that its members blew up a bike loaded with explosives in Beirut's Borj al-Barajneh suburb and that when onlookers gathered, a suicide bomber blew himself up among them.
Lebanese authorities have arrested five Syrians and a Palestinian in connection with the twin bombings.
Moment of second blast in Hezbollah-run Beirut suburb
Nasrallah vowed to avenge the attacks.
"They assume that by killing our men, women, and children, and by damaging our houses and markets, like what they did days ago can shake or weaken our will and determination, or to make us change our stands and vision, they are completely wrong."
"This will increase our determination and persistence, and I tell you, today on these fronts, especially in Syria, we have fought ISIS and others on more than one front, but after this bombing operation, we will go and search for open fronts with ISIS to intensify and strengthen our presence, as this will be a tribute to the martyrs that fell in Borj El-Barajneh," he said.
The explosions were the first attacks in more than a year to target a Hezbollah stronghold in Lebanon, as the Iran-backed group steps up its involvement in the war in neighboring Syria.
Hezbollah has sent hundreds of fighters to support Syrian President Bashar Assad's forces over the border.
Amateur video shows panic during Paris attacks
Government forces backed by Hezbollah and Iranian troops have intensified their fight against mostly Sunni insurgents, including Islamic State, since Russia launched an air campaign in support of Assad on September 30.