The UN Security Council has adopted a binding resolutioncompelling states to prevent their nationals joining jihadists in Iraq and Syria.
US President Barack Obama chaired the session and said nations must prevent the recruitment and financing of foreign fighters.
US and Arab jets bombed Islamic State (IS) targets in Syria for a second day, including oil facilities, the US said.
Mr Obama urged global efforts to dismantle the IS “network of death”.
The US-drafted resolution was adopted unanimously.
The US launched air raids against IS militants in Iraq last month and overnight from Monday to Tuesday expanded the strikes into Syria, with the participation of Gulf Arab allies.
IS now controls several oilfields in Syria and Iraq, and sales of smuggled crude oil have helped finance its offensive in both countries.
Meanwhile, more than 120 Islamic scholars signed an open letter to IS, refuting its ideology.
Muzammil Siddiqi, one of signatories and chairman of the Fiqh Council of North America, that interprets Islamic religious law, said: “”It is forbidden in Islam to kill the innocent.”
“It is forbidden in Islam to kill emissaries, ambassadors and diplomats. Hence, it is forbidden to kill the journalists and aid workers.”
Call to action
Speaking at the UN, British Prime Minister David Cameron said the UK was ready to “play its part” in fighting Islamic State, which he called an “evil against which the whole world must unite”.
He told the UN council session that the Iraq and Syria conflicts were attracting young recruits from prosperous countries.
Mr Obama said “the words spoken here today must be matched and translated into action… within nations and between them, not just in the days ahead but for years to come”.
In his earlier speech to the UN General Assembly he condemned IS, saying “there can be no reasoning – no negotiation – with this brand of evil”.
More than 40 countries had offered to join the anti-IS coalition, he said.
IS aims to set up a hardline caliphate. The well-armed Sunni Muslim militants have seized a huge swathe of Syria and Iraq, forcing whole communities to flee in terror. They have beheaded Western hostages and have persecuted Christians, Yazidis and Shia Muslims, whom they treat as heretics.Multiple air strikes
In the past 24 hours US warplanes hit IS vehicles and arms dumps near Abu Kamal on the Syria-Iraq border and Deir al-Zour in the east of Syria. In Iraq there were strikes west of Baghdad and southeast of Irbil, near Kurdish territory, the US military said.
Twelve of the strikes had been against small-scale oil refineries, which produce between 300-500 barrels of refined petroleum a day and generate as much as $2m a day in revenue, the military added.
It said an initial assessment showed that the strikes had been successful.
There were also air strikes on IS near the border with Turkey.
Later Turkish President Recep Tayyip Erdogan accused the international community of not doing enough to help his country stem the flow of foreign fighters into Syria.
Speaking at the UN Security Council, he said the fighters’ home countries should cooperate better with Turkey to stop them getting through.
The IS advance has created a refugee crisis in Turkey. Aid agencies said some 130,000 Kurdish refugees, most of them from Kobane, crossed into Turkey at the weekend.
The US has launched nearly 200 air strikes against IS in Iraq since August.
The US said Saudi Arabia, the United Arab Emirates, Jordan, Bahrain and Qatar had all “participated in or supported” the strikes on IS in Syria this week.
The strikes on Tuesday also targeted Khorasan, a shadowy group of al-Qaeda fighters in Syria’s Aleppo province. The US military says it is investigating whether the attack killed Khorasan’s leader Mohsin al-Fadhli.
The Dutch government says it will deploy six F-16 fighter jets to join the US-led air campaign. The Netherlands will also send about 130 military trainers to Iraq.
Meanwhile, the UK Parliament will be recalled on Friday to discuss Britain’s possible role in air strikes on IS targets.