"This was a peaceful, compassionate action, with Papuans taking to the streets to raise money for those affected by this latest Pacific natural disaster," said Benny Wenda, president of the United Liberation Movement for West Papua (ULMWP).
"The Indonesian response was to disband the march at the barrel of a gun.
"Armed Indonesian police sought to block activists at several points, forcibly disrupted the procession, and eventually conducted a series of arbitrary arrests."
Vanuatu was hit by two successive cyclones within 24 hours earlier this month. Homes and schools were destroyed, many were forced to flee to evacuation centres, and people lost access to water and electricity for several days.
West Papuans see ni-Vanuatu as "family" - "we naturally want to support them in their hour of need, just as they have always supported us in ours," said Wenda.
"By criminalising this act of solidarity, Indonesia has demonstrated it will not accept any form of Papuan assembly or self-expression."
Wenda said this was not a political protest. Participants did not raise the Morning Star flag or call for independence.
"They only raised awareness and money for a fellow black Melanesian nation that has always supported the West Papuan struggle.
"Indonesia, like the ULMWP, is a member of the Melanesian Spearhead Group (MSG) along with Vanuatu. They have an obligation to allow West Papuans to raise money to stop the suffering of their fellow member."
In March 2015, after Vanuatu was hit by a large cyclone, Papuans in the Yahukimo regency held a similar solidarity fundraiser. In response, police violently broke up the meeting, shooting six Papuan civilians and killing one.
"We must remember that climate change is the sole reason Vanuatu is so vulnerable to cyclones and other natural disasters. Despite producing zero carbon emissions, Vanuatu is being punished for the actions of rich countries and big corporations," Wenda said.
"West Papuans stand with all Pacific nations in our joint fight against this existential threat. Our island is the lung of the world, with its third largest rainforest and thousands of unique plants and animals.
"But Indonesia is ripping down our forests and mountains to build highways, mines, and palm oil plantations.
"To fight for climate justice we must also fight for West Papuan independence and the fulfillment of our Green State Vision."
Wenda reiterated his call for Indonesia to withdraw their military from Papua.
"Demilitarising West Papua is a precondition for this situation to be resolved peacefully. They must also release all 20 Papuans arrested, alongside all political prisoners including Victor Yeimo.
"International journalists must be allowed to report on West Papua.
"Lastly, I repeat the call of 84 countries for Indonesia to finally allow the UN High Commissioner for Human Rights to visit West Papua."
This was an important moment for the world to reflect on what Indonesia was doing to Papua, Wenda said.
"In reclaiming our sovereignty, we are aiming to restore our fundamental human rights - the right to show solidarity, to exercise freedom of assembly, and the rights of our children to live without fear."
The Jakarta government had not responded at press time.