Armed groups that finance their operations by trafficking wildlife in the Democratic Republic of Congo are to be targeted by UN sanctions.
Individuals involved will be subject to travels bans and asset freezes.
The new UN Security Council resolution also renewed an arms embargo on various militia groups in the DR Congo.
The UN has been warning that ivory has become a major source of finance for armed groups and has led to the depletion of elephants in DR Congo.
"This is a huge step forward for reducing human suffering, improving peace and security and strengthening wildlife conservation," Wendy Elliott, species programme manager at the conservation group WWF, said in a statement.
According to a UN experts' report on DR Congo released last week, the killing of elephants in DR Congo "is one of the most tragic consequences of years of war and poor governance'', the Associated Press news agency reports.
In the Garamba National Park in north-eastern DR Congo, a census showed fewer than 2,000 elephants were left in 2012, compared to 22,000 in the 1970s.
Over the last few years, the Lord's Resistance Army rebel group, which originated in Uganda, has had bases in Garamba as well as operating in South Sudan and the Central African Republic (CAR).
A similar resolution was passed earlier this week in relation to the CAR, where poachers have also taken advantage of more than a year of unrest to kill endangered forest elephants.
Next month, the UK is holding an international conference about the illegal trade in wildlife to be hosted by Prime Minister David Cameron.
The new UN resolution provided "another avenue to protect vulnerable species and cut off support to criminal and armed groups,'' AP quotes UK government spokesperson Iona Thomas as saying.
The Convention on International Trade in Endangered Species (Cites) banned the trade in ivory in 1989.
But in recent years poaching has increased across sub-Saharan Africa with criminal gangs slaughtering elephants for ivory markets in Asia, where it is often used to make ornaments.
Eastern DR Congo is also rich in resources and minerals, like gold and coltan - essential for mobile phones, which many armed groups have looted over the years to finance their operations.
BBC DR Congo correspondent Maud Jullien says previous sanctions imposed on militia members accused of trafficking minerals have had little impact and that most of them are continuing their activities as usual.
The new Security Council resolution also expresses concern over reports that the M23 rebels are regrouping.
The recent experts' report found that the group, which was defeated by the Congolese army and UN peacekeepers last year, was forcibly recruiting troops in neighbouring Rwanda.
Rwanda has always denied accusations that it backed the M23.