State Department spokesman Sean McCormack praised Lebanon's armed forces, which he said are performing well under difficult circumstances.
"The Lebanese armed forces are reacting admirably. I know it is a difficult situation anytime you have these terrorist, violent extremist elements embedded in civilian populations, wherever they may be. This is a dangerous, violent group of people that, unfortunately for some of the innocent civilians, need to be dealt with [through] a use of force."
Scores of people have been killed since Sunday, when Lebanese forces began firing on militants of the Fatah al-Islam group, which has been operating out of a Palestinian refugee camp in the northern Lebanese city of Tripoli. The group, suspected of having links to al-Qaida, has threatened to expand the battle to other areas unless the bombardment is halted.
Speaking with reporters, McCormack said the United States mourns the loss of innocent life in the refugee camp, but stressed the need for Lebanon to maintain security and root out militants.
"The people in this group are not petty criminals. These are hardened, violent extremists that will use the most despicable means of violence in order to achieve their ends. And I would just point out that the representative of the PLO in Lebanon also denounced this particular group and actually called upon the innocent Palestinians in this refugee camp to disassociate themselves from this group."
France's new government has also backed Lebanon's actions, stressing the need for the country to maintain its sovereignty and stability. The European Union has voiced concern over the conflict.
Lebanese officials have expressed reservations about entering the refugee camp, where the PLO holds sway. The fighting erupted when Lebanese security forces raided suspected Fatah-al-Islam hideouts searching for suspected bank robbers.