The US-drafted resolution for 4,000 additional peacekeepers in South Sudan authorizes peacekeepers to "use all necessary means, including undertaking robust action where necessary" to protect UN personnel and facilities.
The Juba-based force was also authorized to take "proactive" measures to protect civilians and "promptly and effectively engage any actor that is credibly found to be preparing attacks or engages in attacks."
The resolution brings the total number of peacekeepers in the country to 17,000. Troops from Ethiopia, Kenya and Rwanda will make up most of the new force.
The United Nations Mission in South Sudan (UNMISS) has been criticized for not protecting civilians last month when camps it administers came under attack. It has also been denounced for failing to intervene as government soldiers reportedly gang-raped women outside a UN camp in July.
The resolution passed with 11 votes in favor. Russia, China, Venezuela and Egypt abstained, citing a failure to get permission from South Sudan.
South Sudan criticized the resolution and said it would not cooperate.
"The adoption of this resolution goes against the basic principle of UN peacekeeping operations which is the consent of the main parties to the conflict and also goes against the UN Charter," said Akuei Bona Malwal, the country's UN ambassador. "Consent of South Sudan... would have been important as it would have given the force all the necessary freedoms to carry out the outlined mandate tasks."
US Deputy Ambassador David Pressman said South Sudan's government has actively blocked UN personnel from carrying out work in the country.
"We recognize the importance of government cooperation, but the United States would point to the actions of the government. For while we expect the South Sudanese government to treat the United Nations like the partner that it is, that is simply not happening on the ground in South Sudan today," he said.
Under the resolution, the Security Council will consider an arms embargo if South Sudan impedes the troop deployment.
South Sudan has been riven by conflict since becoming a country in 2011. A civil war broke out in 2013 between government forces loyal to President Salva Kiir, an ethnic Dinka, and rebels led by his former deputy Riek Machar, an ethnic Nuer.
A fragile peace agreement signed last August was to make Machar vice president, but fighting erupted last month between Kiir and Machar's forces as the deal was in the process of being implemented. Machar has since fled the capital and Kiir has appointed a new vice president.
The fighting has exacerbated an already dire humanitarian crisis and hindered aid agencies. More than 2.5 million people have been displaced and some 10,000 killed since the civil war began. About 200,000 people live in UN camps.
cw/cmk (AFP, AP, dpa, Reuters)