The US-drafted resolution was passed unanimously on Tuesday by the UN Security Council. It sets up a committee that would identify to the Council those people who should be blacklisted.
The move heaps pressure on South Sudan's warring parties to reach a peace deal as early as this week, following the death of tens of thousands of people in the country's ongoing conflict, and the displacement of up to two million.
The conflict broke out a little over a year ago, in clashes between forces loyal to President Salva Kiir, and his former deputy, Riek Machar.
The resolution does not explicitly name the two men as possible targets, but says people affected could include "leaders of any entity." It threatens to impose sanctions on those interfering with the peace process.
Talks between the South Sudan government and the rebels are continuing in Ethiopia, with a deadline of this Thursday to reach a peace deal. Multiple deadlines in the past have failed to come up with a decisive agreement.
"Those who frustrate peace must begin to pay the price," said US Ambassador Samantha Power.
But Francis Deng, South Sudan's UN ambassador, said any sanctions would be counterproductive.
"What the president and the government of South Sudan need is encouragement and support, not condemnation."
The resolution comes days after the UN children's agency, UNICEF, warned hundreds of boys were kidnapped in South Sudan's Upper Nile state, in a mass recruitment drive carried out by a militia aligned with government forces.
jr/jil (AP, Reuters, AFP)