State news agency NNA said gunfire was heard, without giving further details of where it was coming from. NNA said several people were injured, some seriously.
As part of 10 days of nationwide demonstrations in Lebanon, protesters had blocked a road out of the northern city of Tripoli near the Beddawi Palestinian refugee camp.
Reuters TV footage showed soldiers and young men throwing stones at each other.
The Lebanese Red Cross said on Twitter that three people were injured there and vehicles were being sent to the scene.
A security source said the army fired into the air to disperse people after gunfire was heard from elsewhere, adding that seven people were injured.A witness said the army was trying to open the road that protesters were blocking and soldiers fired into the air.