Lebanon's premier condemned Tuesday a "dangerous military escalation" by Israel after a security incident at the border led the Jewish state to fire artillery across the frontier.
"Israel has once again violated Lebanon's sovereignty... in a dangerous military escalation," Hassan Diab said on Twitter, in his government's first official response to Monday's shelling.
"I call for caution in the coming days because I fear that things will get worse in light of severe tension at the border," he said.
The Israeli army had said a group of three to five men armed with rifles crossed the UN-demarcated Blue Line in the disputed Mount Dov area, claimed by Lebanon, Syria and Israel.
It said the "terrorists" had fled back to Lebanon after an exchange of gunfire and that Israeli forces had fired artillery into Lebanon "for defensive purposes".
Israeli Prime Minister Benjamin Netanyahu said Monday that the Lebanese Shiite militant group Hezbollah and the Lebanese government "carry responsibility" for the infiltration attempt.
But Hezbollah, which has a presence in the area where the incident occurred, denied any involvement.
It said that reports of Israel thwarting an infiltration from Lebanon are "completely false."
United Nations peacekeeping force UNIFIL said it had opened an investigation into the incident.
Diab on Tuesday accused Israel of trying to "change the rules of engagement," that have existed between the two countries since the end of a month-long 2006 war -- the last direct conflict between the two states.
He also said that Israel was pushing to alter the mandate of UNIFIL before it expires late next month.
In early May, the US ambassador to the UN, Kelly Craft, called on the world body to "pursue serious change to empower UNIFIL or realign its staffing and resources," because the mission was being "prevented from fulfilling its mandate."
Hezbollah chief Hassan Nasrallah swiftly rejected the proposal which he said was an Israeli demand.
The latest border incident follows a July 20 Israeli missile attack on Syrian government and allied positions south of Damascus that killed five people.
Hezbollah, whose fighters back Damascus in the nine-year-old Syrian civil war, said one of its own was among the dead.
Since 2011, Israel has launched hundreds of strikes in Syria, targeting government troops and allied Iranian and Hezbollah forces with the stated aim of ending Iran's military presence in Syria.