Sudanese President Omar al-Bashir has opposed the deployment of international troops in his country, saying Sudan would not be "re-colonised".
Two smaller rebel groups did not sign the deal
The UN is considering sending peacekeepers to Sudan's Darfur region to supplement African Union troops.
Conflict in Darfur between rebels and pro-government forces has killed about 300,000 people in three years.
A report by the International Crisis Group on Monday said a UN peace force was urgently needed in Darfur.
But Mr Bashir said there would be no such force in Sudan, according to reports in state media.
"I swear that there will not be any international military intervention in Darfur as long as I am in power," Mr Bashir was quoted as telling a meeting of his ruling National Congress late on Monday.
"Sudan, which was the first country south of the Sahara to gain independence, cannot now be the first country to be re-colonised," he said.
Peace plan 'flaws'
South African President Thabo Mbeki is currently in Sudan on a one-day visit, with peace moves in Darfur on the agenda.
The ICG warned that the current peace agreement over Darfur had little chance of bringing stability "unless the parties comply strictly and the international community acts decisively to support the peacekeeping mission".
The peace plan was signed by the government and one rebel faction in Nigeria in May.
"There is a very real danger that the international community, in its eagerness to get a deal, has brokered one that is structurally weak," the ICG report said.
"The document has serious flaws, and two of the three rebel delegations did not accept it," it added.
BBC world affairs correspondent Mark Doyle says Mr Mbeki will be told that the current peace agreement, which was pushed through by African and western mediators, may have made the situation worse rather than better.
The rebel movement which signed the peace agreement is from the minority Zaghawa group, while the movement representing Darfur's majority Fur group did not take part, our correspondent says.
The AU-brokered deal has failed to end the violence in Darfur, where more than 2m million people have fled their homes.
The 7,000-strong AU force in Darfur, which operates with th approval of the Sudanese government, has been hampered by a lack of funding and resources.