With the refugee crisis in Europe showing no sign of abating, Tusk said, "Only global efforts supporting refugees and their host communities will be able to bear fruit.
"That is why we want to encourage our partners to increase humanitarian and development aid, as well as refugee resettlement."
Speaking at the G20 summit in China, Tusk, a former Prime Minister of Poland, said the world was struggling to cope with 65 million displaced people, an "unprecedented" number.
His declaration came as a blockade of lorries in conjunction with a human chain on the roads around the French port of Calais caused severe disruption on the roads on Monday.
The protesters are demanding the closure of the 'Jungle' migrant camp. More than 7000 people now live there, in squalid conditions. Many of them try to jump on lorries to reach Britain.
Those living in the camp, who are mainly from the Middle East, Afghanistan and Africa, hope to cross the English Channel, often using people traffickers to try to enter illegally.
Tusk, who, with European Commission President Jean-Claude Juncker, was the official EU representative in China, urged the G20 to "seize the opportunity" of the forthcoming summits on refugees and migrants hosted by the UN and US President Obama to increase aid and resettlements by countries outside Europe.
Taking action was, he noted, "even more important in view of the fact that the practical capabilities of Europe to host new waves of refugees, not to mention irregular economic migrants, are close to the limits."
The G20 brings the leaders of the world's largest economies together to discuss boosting global growth.
Addressing the same issue in Hangzhou, Juncker pointed out that the Commission was preparing an "ambitious external investment plan", using public money to attract private funding in order to tackle the refugee crisis.
He said, "We have to fight against the roots of the refugee phenomena and that is the reason why we have to extend the European investment plan to the outside world."
Juncker also told the summit that Europe's free trade deal with Canada is the "best and most-progressive" trade agreement the EU has ever negotiated.
He said the agreement deserved the full support of the EU's member states and rapid ratification, adding, !Our new trade deal with Canada - CETA - is the best and most-progressive agreement we have ever, as a European Union, negotiated.
"On top of the new opportunities it creates for businesses and citizens, it also marks the new approach to investment protection that is transparent and that is impartial."
Elsewhere, Obama met with Turkish President Recep Tayyip Erdoğan on Sunday, reassuring him that the US remained intent on helping bring plotters of July's coup attempt to justice.
In addition to discussing global economic growth, the summit provides a venue for leaders to discuss other pressing issues. However, not everyone was pleased with the summit's opening. Non-government organisations and journalists decried the lack of access at the summit.