General Jean Kahwaji told Reuters that the radical militants fighting in Iraq and Syria still pose a "great threat" to Lebanon, which was torn apart by a 1975-90 civil war and has been badly buffeted by the Syrian conflict.
“The Army hit them and continues to smashing their plan,” said Kahwaji.
At least 37 Lebanese soldiers were either killed or captured in the battle with ISIL terrorists in the border town of Arsal in recent days.
“But this does not mean that the story is over. They might think of another plan and try another time to cause Sunni-Shiite strife,” Kahwaji warned.
Dozens of militants were killed in Arsal during a five-day battle with the Lebanese army, according to army estimates.
The militants withdrew into the mountainous border zone last Thursday, taking with them 19 captive soldiers.
Kahwaji said the Takfiri militants aimed to turn the Sunni Muslim town of Arsal into a bridgehead from which to advance on surrounding Shiite villages, igniting a sectarian fire storm he said would have destroyed Lebanon.
“The strife in Iraq would have moved to Lebanon - 100 percent,” said Kahwaji, a Maronite Christian.
He said his comments were based on the confessions of an ISIL commander whose detention on August two triggered the battle.
The Commander, Imad Jomaa, had been “fine tuning” the plan at the time of his arrest, Kahwaji said.
Jomaa, 30, was a member of the al-Nusra Front, an Al-Qaeda affiliate in the conflict, but had recently switched allegiance to the ISIL terrorist group.
His confessions had led to the arrest of a number of militant cells in different parts of Lebanon, he added.
The arrival of ISIL fighters waving the group's black flag on the Northeastern border triggered panic in a country that is home to many religious groups at risk from ISIL that has beheaded and crucified its opponents.