Paul Rwarakabije, former commander of the Democratic Liberation Forces of Rwanda (FDLR), made the appeal after Rwanda this week repeatedly threatened to send soldiers into Congo to attack Hutu rebels based in the east of the country.
The rebels have been fighting from jungle bases in the Democratic Republic of Congo.
The former commander said: "The time for war is over. They have to return before they face fire from the Rwandan forces.
"I appeal to these combatants as their former commander to put down their guns and return home peacefully."
Rwanda has twice invaded Congo to hunt down Hutus who took part in the 1994 genocide, killing 800,000 Tutsis and moderate Hutus, and who then fled into eastern Congo once they were defeated.
Rwanda said on Friday it was ready to hold talks with Congo President Joseph Kabila to defuse the tension.
Rwarakabije, who surrendered to the Rwandan government in November 2003 after nearly a decade of fighting in the bush, said he estimated the strength of the rebel forces in Congo to be slightly in excess of 12,000 troops.
"I see no justification in their cause to persist with a rebellion that will cause only limited destruction and will never attain their objectives. This is why I decided to abandon the rebellion," he said.
"The time for war is over. I appeal to these combatants as their former commander to put down their guns and return home peacefully"
former commander of the Democratic Liberation Forces of Rwanda (FDLR)
Upon his return to Rwanda, Rwarakabije, along with four other former rebel senior commanders, was integrated into the Rwandan army.
Rwanda withdrew its army from Congo in 2002, but it accuses the United Nations and the Kinshasa government of failing to disarm and repatriate the rebels and says its soldiers are ready to return.
Rwarakabije has previously accused rebel commanders of spreading misinformation among their fighters about the security situation in Rwanda to deter returnees.
Since his return, up to 1300 of his fighters have followed him back to Rwanda, along with 4000 refugees who had settled in different parts of eastern Congo, he said.