The seven members of the Kharakeh family were crushed to death in the rubble of their two-storey home which was destroyed in an attack on the town of Nabatiyeh in central Lebanon.
A separate attack has wounded two UN monitors who were in an observation post.
The incident comes just days after four UN observers were killed in an Israeli strike.
The main border crossing between Lebanon and Syria is closed after Israeli missiles hit the road on the Lebanese side.
Israel has rejected a UN call for a three-day truce. The UN said children, the elderly and disabled people were trapped and supplies were running short.
Israeli said a humanitarian corridor to the area was open and there was no need for a truce.
Israeli military sources have indicated the fighting could intensify.
The warning came as US Secretary of State Condoleezza Rice continued her mission to the Middle East.
The UN says some 600 people, a third of them children, have been killed by Israeli action in Lebanon.
A total of 51 Israelis, including at least 18 civilians, have been killed during the conflict.