Protesters in Lesbos held a banner shich saud said: "Ferries for safe passage not deportations".
Greece started to send migrants back to Turkey as part of an EU agreement to control the mass influx of people in Europe. Two boats left the Greek island of Lesbos at around 5.30am carrying 131 people, ITV reported.
The European Union signed the controversial deal with Turkey in March as it wrestles with the continent's worst migration crisis since World War II, with more than a million people arriving from the Middle East and elsewhere last year.
Under the deal, Ankara will take back migrants and refugees, including Syrians, who entered Greece illegally. In return the EU will reward Turkey with more money, early visa-travel and progress in its EU membership negotiations.