Greek police clashed with hundreds of refugees hoping to cross to neighbouring countries and travel onwards to northern Europe.
Demonstrations outside the camp in Diavata were triggered by false reports on social media saying restrictions on travel to northern Europe had been lifted, authorities said.
Riot police fired tear gas at dozens of people, some with children in their arms, who responded by throwing stones and bottles as they tried to break a police cordon and reach a road leading to the border.
Several refugees, including children, fainted amid the gas clouds on Saturday.
Protesters lit fires to make the air more bearable, but blazes also erupted from exploding stun grenades.
Greek officials say the migrants have been mobilised by false reports originating on social media that the road to central Europe, tightly sealed to migrants for three years, is open again, and that buses chartered by non-governmental organisations were waiting on the other side of the border with North Macedonia, about 60km (40 miles) to the north of Diavata.
Greek TV station Ant1 showed messages sent over social media earlier this week, in Arabic, from a purported NGO called "Caravan of Hope" advising refugees Greece was to open the border with North Macedonia on 5 April at noon.
Most were not residents of the camps, but came from all over Greece to reach the North Macedonian border and had started setting up tents near the camp.
Around 100 tents had been pitched in the field next to the camp, which was heavily guarded by police.
People refused to leave despite calls by ministers to return to accommodation centres and warnings onward travel would be impossible.
"It's a lie that the borders will open," migration minister Dimitris Vitsas told Greek state television ERT on Friday.
Tens of thousands of refugees, mainly from Syria, Iraq and Afghanistan, have been stuck in Greece since 2016, when Balkan countries shut their borders, closing the main passage towards northern Europe.
Additional reporting by agencies
