Lebanese Prime Minister Tammam Salam is calling Saturday's raid on a border town by Syrian rebels an attack against Lebanon and its people.
Salam says his government will not tolerate chaos and let matters get out of control, adding that the army is working to restore security and stability to the town of Arsal.
It was one of the most serious incursions into Lebanon in the three-year-old Syrian civil war.
Lebanese officials say the violence began when security officers arrested a member of the Nursa Front rebel group at a checkpoint.
Rebel gunmen stormed into Arsal, demanding his release. They seized the police station and briefly held a number of soldiers hostage.
Masked gunmen and Lebanese army vehicles were reported to be seen in the streets of Arsal during much of the day.
Reports say the fighting has killed at least seven Lebanese soldiers and two civilians.
The U.S. State Department is strongly condemning Saturday's attack and says it supports Lebanon's security, sovereignty and policy of staying out of regional conflicts.
Violence stemming from the fighting in Syria often spills over into Lebanon.
Lebanese-based Hezbollah extremists have fought alongside Syrian government forces against the rebels trying to topple President Bashar al-Assad.
Some information for this report comes from AP and Reuters.