United Nations peacekeepers in the Liberian capital have arrested up to 250 people following days of unrest in which at least 14 people died.
Liberia hosts the world's largest peacekeeping operation
UN envoy Jacques Klein said the deaths and injuries, which left more than 200 people in hospital, were caused by clubbing, beatings and machete wounds.
Monrovia is now calm with UN helicopters hovering overhead.
The violence is the worst seen in the city since former president Charles Taylor was forced into exile.
Following the passing of a disarmament deadline on Sunday, UN peacekeepers are conducting door-to-door searches for weapons, and attempting to reimpose their authority.
Some 95,000 fighters have handed over weapons in the UN programme.
Mr Klein said there were several flash points which were used by former combatants, especially those linked to Mr Taylor, to try to destabilise the country.
"What we are seeing are the death throes of the [old] regime," he told the BBC.
The violence is a reminder of how volatile Liberia remains
Areas on the outskirts of Monrovia remain tense. Several churches and mosques were attacked during the clashes which began last Thursday, and a curfew was put in place.
"In the old days they used tribal differences which don't seem to be working now so now they've hit on religious differences," he told the BBC's Network Africa.
The violence was sparked, Mr Klein says, by competition between vendors for space in a market and further exacerbated by an internal leadership election among former Lurd rebels and then former Taylor fighters, criminals and thugs joined in, he said.
However he said there was no serious threat to peace in the country.
"This is what we call a bump in the road," he said
Last week, parts of city suburbs were sealed off as gangs fought running battles.
The violence also forced the UN to postpone repatriation of refugees from neighbouring Guinea.
Liberia's interim leader Gyude Bryant - who heads a transitional power-sharing government set up to organise elections - blamed hooligans.
The unrest was one of the most serious outbreaks of violence in Liberia since the full deployment of some 15,000 UN peacekeepers in Liberia as part of a peace deal to end 14 years of civil war.
The chief Liberian peace negotiator for the West African community, Abdusalami Abubuakar, has now arrived in Monrovia to try to bring rival rebel faction leaders back within the peace process.
Fighters from the largest rebel movement known as Lurd are drawn from the mainly-Muslim Mandingo ethnic group.
And they have clashed with fighters which draw their support from Christian communities.
But the BBC's Dan Isaacs says that tensions and mistrust are complex and run very deep.