More than a dozen members of the Lebanese military were killed last month during the capture of a compound held by Sunni religious leader Ahmad Assir, a harsh critic of Hezbollah and the Assad regime.
Guerrilla forces with Hezbollah are fighting alongside pro-government forces in Syria.
Regional authorities in Sidon met Monday to review the security situation in the area. Demonstrations in the city are discouraged and army patrols would intensify in the wake of the June raid, the official National News Agency reports.
Sidon officials said the military would not be lenient with those threatening Lebanon's national security.
Syrian civil war has threatened to spill over the Lebanese border. The Syrian government played a major role in the affairs in Beirut until revolution in Lebanon in 2005 ensured the country's sovereignty.
Lebanese President Michel Suleiman met Monday with military officials. He said the national military was tasked with preventing tensions from spiraling out of control.