Civil society groups called protests in Goma on Wednesday to denounce delays in implementing the M23 insurgent force withdrawal.
Regional leaders brokered a ceasefire in November under which the Tutsi-led group, which launched a fresh offensive last year, was meant to pull out of recently captured positions. The deadline for this was Jan. 15, according to DRC's presidency.
"The population is tired of seeing this useless East African Community [EAC} force turn into an observer mission that watches how they massacre us," said Espoir Mwinuka, an activist with the Lucha, a group of young activists, who co-organized the march.
"On the ground, they are doing nothing but serving as a shield for the enemy, so this force has no reason to be here," said Josue Wallay, another Lucha activist.
On arrival in Goma city center, the march was stopped by police who fired tear gas.
Journalists were threatened by police and an officer threw a tear gas grenade at the group of reporters, hitting an AFP correspondent in the head.
A journalist was injured while fleeing.
Two others were arrested along with six protesters and released after three hours in custody.
About 100 demonstrators gathered near a roundabout to march against the East African Community (EAC) force, which they said was ineffective.
A local police commander denied any arrests were made. The EAC did not immediately respond to a request for comment.
Several thousand soldiers from Kenya and Burundi have recently been deployed to reinforce the DRC army and the United Nations to fight armed groups in the east of the DRC.
The mainly Tutsi M23 rebels took up arms again in late 2021, prompting the deployment of the the regional force.
Since the end of October and despite declarations of a ceasefire and troop withdrawals, M23 has continued to clash with the DRC military and other armed groups.
The M23's latest offensive has displaced at least 450,000 people and sparked a diplomatic crisis between DRC and neighboring Rwanda.
Congo accuses Rwanda of fueling the conflict by supporting the rebels - an accusation levelled also by Western powers and United Nations experts. Rwanda denies this.
Several protests have taken place in Goma over the past months, the latest directed at Rwanda and the ceasefire deal.
Complaints that U.N. peacekeepers have failed to protect civilians against long-standing militia violence spurred deadly protests in July.
South Sudan's contingent of 750 soldiers is expected to arrive soon.
This report was prepared with information sourced from Reuters and Agence France-Presse.