Lebanese movement Hezbollah also said four of its fighters were killed in an Israeli strike.
Israeli forces and Hezbollah, a Hamas ally, have traded near-daily fire since war broke out on October 7 between Israel and the Palestinian militant group in the Gaza Strip.
In the past few days, a series of Israeli strikes has injured officials from Lebanese and Palestinian armed groups in southern Lebanon.
The source said an Israeli strike “targeted a local Hezbollah official in the town of Bint Jbeil” and the official was “seriously injured”.
Lebanon’s official National News Agency (NNA) said “an enemy drone targeted a car near the hospital” in Bint Jbeil, near the country’s southern border with Israel.
An AFP journalist on the ground saw the targeted car, severely damaged with a hole punched through its roof.
The Israeli military said in a statement on X, formerly Twitter, that “an aircraft struck a vehicle in which Hezbollah terrorists were identified in the area of Maroun El Ras,” which is on the edge of Bint Jbeil.
This came during a series of Israeli strikes against Hezbollah targets, it said.
In Tayr Harfa, further west of Bint Jbeil, two people were seriously wounded in an Israeli strike on a house, according to NNA.
Israel’s military said it struck “military structures and a military site” there and in Maroun El Ras.
Hezbollah later announced the death of four of its fighters “on the road to Jerusalem” — the phrase the group has been using to refer to militants killed by Israeli fire since hostilities began.
The movement said two of those were from the town of Tallouseh, about four kilometres from the Israeli border.
During the evening, NNA said Israel had hit targets in the town.
Hezbollah claimed it had since launched seven new attacks against Israeli border positions.
Separately, the Al-Quds Brigades, the armed wing of militant Palestinian group Islamic Jihad whose fighters are present in Lebanon, said two of its members were killed.
They died “at the border with occupied Palestine, in the south of Lebanon,” said a statement from the group, which is fighting in Gaza as an ally of Hamas.
On Saturday, senior Hamas officer Bassel Saleh survived an Israeli strike on his car in the Lebanese border town of Jadra, security sources said, adding that two others were killed.
On Thursday, an Israeli drone strike seriously wounded a Hezbollah commander in the southern city of Nabatiyeh, with the group later firing a salvo of rockets into northern Israel.
Cross-border fire since the start of the Israel-Hamas war has killed at least 238 people in Lebanon, most of them Hezbollah fighters but also including around 30 civilians, according to an AFP tally.