Hezbollah's deputy leader Naim Qassem, in his first public address since Israel assassinated the group's chief Hassan Nasrallah last week, said the movement is ready to confront any Israeli ground invasion of Lebanon.
Israel will not achieve its goals, he said.
"We will face any possibility and we are ready if the Israelis decide to enter by land and the resistance forces are ready for a ground engagement," he said.
Israeli forces have dealt multiple blows to Hezbollah in a two-week wave of attacks on targets in Lebanon that has eliminated several commanders. The possibility that Israel's next move might be to send ground troops and tanks over the border is on many minds.
In other developments, the Palestinian group Hamas said an Israeli airstrike killed its leader in Lebanon in the city of Tyre on Monday, and another Palestinian organization said three of its leaders died in a strike in central Beirut - the first such hit inside the capital's limits.
The killings were the latest in a wave of intensified Israeli attacks on militant targets in Lebanon, part of a conflict also stretching from the Palestinian territories of Gaza and the occupied West Bank, to Yemen, and within Israel itself.
Hamas said its leader in Lebanon, Fateh Sherif Abu el-Amin was killed along with his wife, son and daughter, in a strike that targeted their house in a refugee camp in the southern city of Tyre in the early hours of Monday.
Another group, the Popular Front for the Liberation of Palestine (PFLP), said three of its leaders were killed in a strike that targeted Beirut's Cola district.
This was the first time Israel had struck Beirut beyond its southern suburbs in a campaign which culminated in the assassination of Nasrallah last week in a succession of heavy air strikes.
The strike against the PFLP hit the upper floor of an apartment building, Reuters witnesses said. There was no immediate comment from the Israeli military.
The latest attacks indicated Israel has no intention of slowing down its offensive on multiple fronts even after eliminating Nasrallah, who was Iran's most powerful ally in its "Axis of Resistance" against Israeli and US influence in the region.
Israel's intensified attacks against the Iran-backed Hezbollah in Lebanon and Houthi militias in Yemen have prompted fears that Middle East fighting could spin out of control and draw in Iran and the United States, Israel's main ally.
Iranian Foreign Ministry spokesperson Nasser Kanaani said Tehran would not leave any of Israel's "criminal acts" go unanswered. He was referring to the killing of Nasrallah and an Iranian Guard deputy commander, Brigadier General Abbas Nilforoushan, who died in the same strikes on Friday.
Lebanon's Health Ministry says more than 1,000 Lebanese have been killed and 6,000 wounded in the past two weeks, without specifying how many were civilians. One million people - a fifth of the population - have fled their homes, the government says.
The escalation has put Beirut on edge, with Lebanese fearful that Israel will expand its military campaign.
"There is nothing else to say or add, except God save Lebanon," Beirut resident Nawel said. "What will happen to me is the same as what can happen to anyone."
