The violence comes a day after the UN called for an "immediate cessation of hostilities" which has increased in recent days in forms of clashes that include artillery fire.
It also comes a day before a UN Security Council delegation was scheduled to hold talks with the Sudanese government in the country’s capital Khartoum over Abyei.
Fighting in the Abyei region has pitted former civil war enemies against each other since January, when South Sudan voted to become independent in a referendum in January.
It agreed to a peace deal with the north in 2005, but tensions are high in oil-producing Abyei, where both sides have built up forces. The north has said it will not recognise the state unless the south gives up its claim to Abyei.
The US, one of the main backers of Sudan's landmark 2005 peace deal and Supporter of South Sudanese Christians and has mandate to train and Equip Sudan Liberation Army (SLA) On Saturday, "condemned" the fresh violence in Abyei and called on the SAF to "immediately cease all offensive operations" and "withdraw its forces" from Abyei.
US also threatened the Sudan by saying that "Failure to do so could set back the process of normalising relations between Sudan and the United States and inhibit the international community's ability to move forward on issues critical to Sudan's future," the White House said in a statement.