North Sudanese armed forces seized control of the oil-producing Abyei region on Saturday, forcing tens of thousands to flee and sparking an international outcry less than seven weeks before south Sudan secedes to form a new nation.
"We will not go back to war, it will not happen," Kiir told reporters in Juba, the capital of south Sudan which plans to become independent on July 9.
Abyei was a key battleground in Sudan's last civil war and is symbolic for both sides. The region is used all year round by the Dinka Ngok people, who have strong ethnic links to the south, and for part of the year by northern Misseriya nomads.
Analysts fear north Sudanese land grab could spark a return to full-blown conflict, a development that would have a devastating impact on the region by sending refugees back across borders and creating a failed state in the south at birth.
Khartoum has defied U.S. and U.N. calls, saying it will not withdraw from land it says belongs to the north. A monitoring group that uses satellite images said it had spotted more north Sudanese armor in positions that could be deployed to the area.
Southern Information Minister Barnaba Benjamin said the north was moving "thousands" of Misseriya tribesmen, who are supported by Khartoum, into the disputed into Ngok villages.
Southerners voted for secession in a January referendum which followed a 2005 peace deal that ended decades of civil war between the two halves of Africa's largest country by land area.
ENOUGH FIGHTING
Kiir called on northern President Omar Hassan al-Bashir to pull out his forces from the area that contains fertile grazing land and said it would not derail the south's secession plans.
"We fought enough ... We made peace," he said. "The south will become independent on July 9, whether the north recognizes the south or not that is not the problem."
A Washington-based monitoring organization, Satellite Sentinal Project, said imagery and analysis indicated the north Sudanese armed forces had gathered heavy armor and artillery around El Obeid, about 430 km (270 miles) north of Abyei.
John Prendergast of Enough Project, which supports Sentinel, said in a statement the imagery showed the Sudanese government "is prepared to intensify military operations in Abyei and along the contested border, where most of Sudan's oil lies."
He said Khartoum "seeks to intimidate the government of Southern Sudan and the international community into deeper compromises at the negotiating table over critical issues of border demarcation, the disposition of oil revenues, and the future status of Abyei."
Abyei remains the most contentious point in the countdown to the secession of the south, the source of 75 percent of the country's 500,000 barrels a day oil production.
The 2005 deal promised Abyei residents their own referendum over whether to join north or south, but that did not take place as neither could agree who was qualified to vote.
The peace deal created a coalition government dominated by Bashir's National Congress Party and the former southern rebel Sudan People's Liberation Movement (SPLM), headed by Kiir. Both were also allowed to keep their own armies.
The coalition government is to be dissolved on the secession of the south which now has its a semi-autonomous government.