The strongly-worded US-drafted text is aimed at piling pressure on South Sudan's warring sides as they head into a new round of peace talks in Ethiopia next month to end the four-year war.
The measure "expresses the council's intention to consider all appropriate measures against those who take actions that undermine the peace, stability and security of South Sudan, including an arms embargo, to deprive the parties of the means to continue fighting and to prevent violations of the cessation of hostilities agreement," a Security Council diplomat said.
Under the text, the UN force would still be staffed by 17,000 troops and police, including a 4,000-strong regional protection force and 2,101 police.
A diplomat speaking on condition of anonymity stressed the resolution was primarily focused on renewing the peacekeepers' mandate, with an arms embargo -- long sought by the US -- a theoretical possibility only.
More than half of South Sudan's population, ravaged by a civil war since December 2013, faces extreme hunger -- a 40 percent increase over last year -- according to a recently published report by three UN agencies.
A UN rights commission last month said there was sufficient evidence to charge at least 41 senior officers and officials with war crimes and crimes against humanity.
South Sudan won independence from Sudan in 2011, with critical backing from the United States, which remains Juba's biggest aid donor.
With the war now in its fifth year, Ethiopia is leading a regional peace effort, hosting talks between the government and rebel groups that have yet to produce a breakthrough.
A ceasefire deal agreed in December has not taken hold, even though the level of violence has decreased.
The United States failed in late 2016 to garner enough support for a ban on weapons sales after eight countries including Russia, China, Angola, Egypt and Senegal abstained.
Nine votes are required to adopt a resolution in the 15-member council.
Despite the defeat, the United States has continued to call for an arms embargo, with the support of Britain and France.
A UN rights commission last month said there was sufficient evidence to charge at least 41 senior officers and officials with war crimes and crimes against humanity.
The commission's report documented extraordinary cruelty. Some victims were beheaded, burned alive or had their throats cut, others had their eyes gouged out or were tortured.
Addressing a recent African Union summit, UN Secretary-General Antonio Guterres dropped his usual reluctance to criticize leaders and bluntly said of South Sudan's leaders that he "had never seen a political elite with so little interest in the well-being of its own people."
Eyewitness? Submit your stories now via social or:
Email: eyewitness@pulse.ng
