"The sensationalized 'Kishishe massacre', a fabrication of the DRC government that it attributed to M23, has quickly spread without any investigation of the facts by any credible entity," the Rwandan government said on Wednesday.
"The incident was in fact an armed confrontation between M23 and illegal armed groups allied to" the DRC armed forces, it said.
"Accusing Rwanda of support to the Congolese armed group M23 is wrong and distracts from the real cause of continued conflict in eastern DRC, and its impact on the security of neighboring states, including Rwanda," it added.
Kinshasa accuses its smaller neighbor Rwanda of backing the M23, a claim denied by Rwanda, but supported by the United States, France, Belgium and UN experts.
The militia has seized territory in the DRC's volatile and mineral-rich east in recent months, ratcheting up tensions with Rwanda.
Talks between DRC and Rwanda in Angola paved the way for a truce agreement last month but Kinshasa subsequently accused M23 of massacring civilians in the village of Kishishe, with a UN investigation saying 131 people had been killed.
M23 has denied being behind the massacre, blaming "stray bullets" for the deaths of just eight civilians.
Kigali has repeatedly accused Kinshasa of colluding with the FDLR -- a former Rwandan Hutu rebel group established in the DRC after the 1994 genocide of mainly Tutsis in Rwanda.