Obasanjo told journalists after the talks in the rebel-held town of Jomba in North Kivu province: "I know now what he wants. I know that a ceasefire is like dancing tango, it cannot be done by one only."
The meeting came just hours after fresh fighting broke out between the CNDP and the DR Congo military.
"Heavy fighting broke out around 7am [05:00 GMT]" in Ndeko, a village close to the strategic town of Kanyabayonga, Lieutenant Colonel Jean-Paul Dietrich of Monuc, the UN mission in DR Congo, said.
Yvonne Ndege, Al Jazeera's correspondent in Jomba, said that Nkunda had told Obasanjo that his forces had respected previous ceasefires.
"He feels that ceasefires have been broken by Monuc, the Congolese army and Mai Mai fighters [which support the government]," she said.
"He pointed out to Obasanjo that he feels that the political institutions in DR Congo are not doing their job. He has various economic demands and said that [president Joseph] Kabila has acted like a dictator. He said was concerned about the accumulation of large debts by the country."
Nkunda's agreement to work towards a peace deal with Kinshasa comes a day after he told Al Jazeera that he was ready to negotiate.
"There are no conditions, we are asking only for negotiations, direct negotiations with our government and we ask him [Obasanjo] to get us a mediator," he told Al Jazeera.
"But other things we cannot expect from him, because it will be a matter for talking with our government."
Obasanjo had already met Joseph Kabila, DR Congo's president.
More than 250,000 people have been displaced by fighting between the army and the CNDP, which claims to be acting in the interest of ethnic Tutsis in the region.
|Thousands of Congolese civilians have fled
their homes to avoid the fighting [EPA]
At least 100 people have been killed since fighting broke out in September, despite the presence of about 17,000 UN troops - the largest UN peacekeeping force in the world.
Kinshasa says that the CNDP is receiving assistance from neighbouring Rwanda, a claim that Kigali denies.
There are fears the country could slide into a ruinous war similar to the 1998-2002 conflict that drew in more than half a dozen African nations.
In the wake of that conflict, fighters backed by Uganda and Rwanda seized vast swaths of territory rich in coffee, gold and tin in the east.
Angola and Zimbabwe sent tanks and fighter planes to back DR Congo's government in exchange for access to lucrative diamond and copper mines to the south and west.
Eastern Congo has been unstable since millions of refugees spilled across the border from Rwanda's 1994 genocide, which saw more than 500,000 ethnic Tutsis and moderate Hutus slaughtered.