Australia's Parliamentary Secretary for Pacific Island Affairs Richard Marles will join the United Nations Security Council debate on climate change and security.
Mr Marles will also meet ambassadors representing Pacific nations and small island states in other parts of the world, as well as UN officials.
He will then visit Cuba to develop closer aid cooperation in the Pacific, including in health.
The visit underscores Canberra's policy change as a former foreign minister, Alexander Downer, had written to Papua New Guinea's health minister in 2007, warning Cuban doctors could destabilise the Pacific.
Sir Peter Barter said at the time Mr Downer's letter was totally out of place.