Lebanon on Monday condemned the spillover of fire from Syrian rebel and regime forces onto its territory and said it would protest to the Arab League.
The decision comes after two Lebanese citizens were killed by artillery fire from Syria on Sunday.
"The safety of every Lebanese citizen and village is the responsibility of the Lebanese state, and any attack from any side is unacceptable," Social Affairs Minister Wael Abu Faour said after a ministerial meeting.
He said Lebanon's foreign ministry would "undertake all necessary measures and communications to ensure all sides bear their responsibilities and do not repeat such attacks."
Abu Faour said the measures would include "the preparation of a memorandum to the Arab League," which would "protest... any attack regardless of which party was responsible for it."
The decision, taken by select ministers of the Hezbollah-dominated caretaker government, comes a day after two separate incidents of fire from Syria spilling into Lebanon.
Shells have regularly strayed into Lebanon from Syria, on occasion killing Lebanese citizens, but Sunday's incidents resulted in the first deaths in Hezbollah-strongholds in the border region, reportedly by rebel fire.
Security sources said the artillery fire continued on Monday, with two shells landing in the town of Qasr, where one person was killed a day earlier.
Lebanon, which has officially followed a policy of "dissociation" from the Syrian conflict, has been reluctant to publicly blame either regime forces or rebel fighters for fire hitting its territory.
The war in neighbouring Syria has exacerbated existing tensions in Lebanon's multi-confessional population and fractious political system.
Abu Faour said the military was taking unspecified measures "to protect Lebanese citizens from any attack," without detailing whether the army would return fire across the border.
After the attacks on Sunday, the Lebanese army said its units "were deployed widely across the area and took measures in the field necessary to protect people and respond to the source of the attack as appropriate."