On Saturday and Sunday night demonstrators, who had called for a "week of rage", lobbed stones, firecrackers and street signs at riot police, who fired tear gas and rubber bullets to clear a road leading to parliament.
In months of protests that have gripped the country and pushed Mr Hariri to quit, politicians wrangling over cabinet seats have failed to agree a new government or a rescue plan.
On Jan. 18, at least 377 people were wounded - both protesters and members of the security forces - according to a toll compiled by AFP from figures provided by the Red Cross and Civil Defence.
Security forces and the military were girding themselves for more violence, following protester calls for more rallies on Sunday.
January 18's clashes began after dozens of protesters threw stones and plant pots at security forces, and tried to charge police lines near parliament with traffic signs.
A worsening economic crisis means many can not find jobs, pay for basic goods, or even withdraw their money from banks.
"There was no justification for the brutal use of force unleashed by Lebanon's riot police against largely peaceful demonstrators in downtown Beirut", said Michael Page, deputy Middle East director at HRW.
The security forces responded with water cannon and thick tear gas.
Police fired tear gas and water cannon to disperse crowds near the parliament in Beirut on Saturday and Sunday.
Government forces blocked access to some buildings in central Beirut with razor wire, closing off access to areas that included a popular tourist site.
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The deal was signed by Fayez al-Serraj, leader of the GNA which has struggled to defend itself against an offensive by the LNA. Since Haftar's forces launched an offensive in Tripoli in April there have been global efforts to try to contain the crisis.
The Red Cross said more than 145 people were injured, including 45 who needed treatment in hospital.
Police accused protesters of rioting and posted pictures of officers being treated for injuries from pillars stripped of tiles that they said the demonstrators had been flinging at security personnel.
It accused the riot police on January 18 of "launching tear gas canisters at protesters' heads, firing rubber bullets in their eyes and attacking people at hospitals and a mosque".
"Another day without a government, another night of violence and clashes", United Nations envoy to Lebanon Jan Kubis said on Twitter.
Lebanon's Internal Security Forces (ISF) urged people to remain calm and said otherwise it would be forced to repel them.
Demonstrators say the Lebanese political elite has ignored their calls for forming an independent government to tackle the deepening crisis.
Protesters have demanded a new government be comprised exclusively of independent experts, and exclude all established political parties.
"We will not pay the price", chanted some protestors, referencing the national debt, which now stands at $87 billion (€78 billion) or 150% of GDP.
Prime Minister-designate Hassan Diab has not been able to form a Cabinet over political bickering, a month after his nomination amid a severe economic and financial downturn.