Saniora's first comment since fighting erupted Wednesday came as conditions appeared to be mostly calm in Beirut's Muslim sector a day after Shiite gunmen swept through the area.
Elsewhere around the country, however, violence appeared to be on the rise.
Some 25 people have died in four days of clashes.
In a Sunni Muslim neighborhood of the capital, a Shiite shop owner opened fire on a funeral procession Beirut, killing two and wounding six, police and witnesses said.
In a mountain town east of Beirut, Hezbollah accuses a pro-government Druse group of kidnapping three of its members and killing two of them.
A statement held Druse leader Walid Jumblatt "personally responsible" for the safety of the third man.
In Beirut's western Muslim sector, though, the focus of the fighting, most Hezbollah gunmen had pulled out leaving just small bands of their Shiite Amal allies to patrol the streets.
The funeral shooting and the reported kidnapping and execution underlined the state of lawlessness and the sharpened sectarian tensions that have engulfed the country since Sunni-Shiite fighting erupted in the capital's Muslim sector on Wednesday resulting in Hezbollah's takeover of Sunni neighborhoods.
In his nationally televised speech, Saniora also said Lebanon can no longer tolerate Hezbollah having weapons - signaling that the US-backed government was toughening its stand against the Shiite militant opposition group despite its loss of ground in street fighting in Beirut.
But Saniora also appeared to be retreating from the government decisions that triggered the street confrontation, offering a compromise that would effectively shelve them.
The offer, however, is unlikely to be accepted by Hezbollah and its allies who have already rejected a similar compromise from Sunni majority leader Saad Hariri earlier.
Hezbollah moved Thursday to seize the Sunni neighbourhoods of Beirut in a show of force after its leader Hassan Nasrallah accused the US-backed government of "declaring war" on his group when it declared the organization's communications network illegal and ordered the removal of the airport security chief for alleged ties to the militants.
Saniora's harsh criticism of Hezbollah was bound to further escalate the fierce power struggle between the government and Syrian- and Iranian-based opposition.
The dream of democracy in Lebanon has been dealt "a poisonous stab by the armed coup carried out by Hezbollah and its allies," he said, saying Beirut was an "occupied, besieged" city by Hezbollah and its allies.
Addressing the army he said, "I call on ii once again to impose security on all, in all areas, deter the gunmen and immediately remove them from the street ... to restore normal life."
Although he talked tough, his embattled government appear unable to move against Hezbollah or force the army to act.
The army has stayed out of the fighting and has deployed troops on the last 2 hours.
In the funeral attack, police said troops have captured the lone gunman in the Sunni Beirut neighbourhood of Tarik Jadideh.
Source: By DDNEWS