Hundreds of people joined a general strike in Mytilene, Lesbos, on Wednesday, against government plans to erect new migrant detention centres on the island.
Similar protests took place across the Northeastern Aegean islands, including Chios and Samos.
"The government wants to implement by force against the will of the citizens of the islands to make a new hotspot, and we are against it," said one protester.
He added, "we want people to go to the mainland Greece, and then after that with the fast-track procedures to have their documents and go to the countries of their desire."
The refugee crowding in the Greek camps had temporarily eased following a deal between the EU and Turkey but has worsened in recent months. With 74,613 arrivals in 2019, according to the UNHCR, Greek islands continue to be the main entry point for illegal immigration in the EU.