The group also triggered a vast humanitarian crisis as it closed in on the provincial capital Goma.
On Wednesday morning, armed men claiming to be Congolese patriots attacked M23 positions near Kibumba.
M23 fighters repulsed the attack and the army later arrested the assailants, the army official added.
Goma
Fresh clashes with M23 rebels erupted Wednesday near the eastern DR Congo city of Goma, according to officials, rupturing weeks of relative calm in the troubled region.
A Tutsi-led group, the M23 has won a string of victories against the army and enemy militias since re-emerging from dormancy in late 2021, capturing swathes of North Kivu province.
The group also triggered a vast humanitarian crisis as it closed in on the provincial capital Goma, a trade hub of over one million people.
On Wednesday morning, armed men claiming to be Congolese patriots attacked M23 positions near Kibumba, about 20 kilometres north of Goma, according to an army official who requested anonymity.
Repulsed attack
M23 fighters repulsed the attack and the army later arrested the assailants, the army official added.
Fataki Sebatutsi, a civil society leader in Kibumba, also told AFP that clashes had occurred.
A precarious calm had reigned for several weeks prior to the attack, with troops from the regional East African Community (EAC) military force deploying to the region to oversee an intended M23 withdrawal.
M23 leader Bertrand Bisimwa tweeted on Wednesday that the "Kinshasa government coalition" had attacked its positions.
M23's advance
Kibumba marked the furthest extent of the M23's advance towards Goma, but the group announced a withdrawal from the settlement on December 23, which took place under the supervision of the EAC force.
The M23 retreated from the settlement but stayed put in the surrounding hills.
The group has since withdrawn from several other areas that it conquered, but the Congolese army has cast such retreats as diversion tactics.
The EAC force comprises Kenyan, Burundian, Ugandan and South-Sudanese troops, with many contingents arriving in eastern Democratic Republic of Congo only within the last several weeks.
It is meant to supervise a staged withdrawal of the M23 from the region, but many locals are disappointed that the force is not taking the fight directly to the rebel group.