The Security Council voted Thursday in favour of extending sanctions against South Sudan until May 31, 2020.
It includes an arms embargo, asset freezes and travel bans on some officials over their role in the country's civil war.
Information Minister Michael Makuei says the arms blockade only benefited rebels who had refused to sign a peace deal last September.
The UN Security Council's decision to renew an arms embargo on South Sudan was "anti-peace" and will weaken the government's fight against rebels, a senior minister told AFP on Friday.
The Security Council voted Thursday in favour of extending sanctions against South Sudan until May 31, 2020.
It includes an arms embargo, asset freezes and travel bans on some officials over their role in the country's civil war, now heading towards its sixth anniversary.
Information Minister Michael Makuei said the arms blockade only benefited rebels who had refused to sign a peace deal last September aimed at ending a conflict that has killed hundreds of thousands and displaced millions.
"Any arms embargo at the moment is an anti-peace measure," Makuei told AFP.
"There are people who do not want peace in South Sudan... All this is done in order to weaken the government so that it can be overthrown by the opposition."
Makuei referred in particular to the rebel group of former South Sudanese General Thomas Cirillo Swaka, who has been leading the National Salvation Front since 2017, fighting the government army in the country's south.
The US-drafted Security Council resolution was adopted by a vote of 10 in favour with five abstentions.
Resolutions in the 15-member council require a minimum of nine votes for adoption.
The three African countries on the council—Equatorial Guinea, Ivory Coast and South Africa—refused to support continued sanctions, arguing it would not push the country's rivals closer to peace.
The US criticised the three, saying they had shown "an unwillingness to stop the flow of weapons to one of the continent's deadliest civil conflicts."
Under the September peace agreement, President Salva Kiir agreed to set up a unity government with longtime rival Riek Machar, who is to return from exile.
The accord—which was not signed by Cirillo or former army chief Paul Malong—provided for the formation of a power-sharing transitional government by May 12, but that provision has been delayed by six months.