Lebanese President Michel Aoun said on Saturday that any Israeli attempt to violate Lebanon's sovereignty would be met with the "appropriate response", in a statement released by his office.
"Any attempt to hurt Lebanese sovereignty or expose the Lebanese to danger will find the appropriate response," the statement said.
It said Aoun was reacting to recent remarks in a letter at the United Nations by Israel's UN ambassador, which amounted to a "masked attempt to threaten security and stability" in southern Lebanon, but did not say what the remarks were.
Israeli Intelligence Minister Yisrael Katz said on Thursday that all of Lebanon would be a target if Hezbollah fired on Israel.
Aoun's comments also followed warnings this week by the leader of the armed Lebanese Shi'ite group Hezbollah, a political ally of the president, against any Israeli aggression.
Sayyed Hassan Nasrallah said the group's rockets had the ability to strike Israel's nuclear reactor at Dimona and its military infrastructure - an apparent warning against any Israeli military action that he said might be approved by the new US president, Donald Trump.
In 2006 Israel fought a month-long war against Hezbollah in south Lebanon.
Since then, hostilities between them have been limited to occasional firing across the border and air strikes by Israel against Hezbollah leaders and military equipment in Syria, where the group is fighting in support of President Bashar al-Assad.
Trump's administration has been vocal in its criticism of Hezbollah's patron Iran and in its support for Israel.