Hundreds of migrants gathered at a fence along the Greek-Macedonian border in Idomeni on Sunday, demanding that authorities open the border and let them pass.
"We heard the border opens today," a Syrian refugee said on Greek radio.
Some migrants held pieces of white cloth to symbolize that they are travelling in peace, state broadcaster ERT reported.
More than 50,000 migrants have been stranded in Idomeni and elsewhere in Greece after Macedonia declared its borders closed to all travellers without valid passports and visas earlier this month, matching similar measures from Serbia, Croatia and Slovenia.
Greece's refugee crisis committee estimates that 11,500 migrants remain at Idomeni's makeshift camp, which was initially set up to host no more than 2,000 people. Conditions there deteriorated in recent weeks, with rights groups warning the cold, muddy and unhygienic site could become a humanitarian disaster.
Reports by the state broadcaster later Sunday showed that the situation had eased slightly after police prevented buses of left-wing activists from reaching the camp. The Greek anti-fascist KEERFA group had intended to assist the stranded migrants in breaking through the Macedonian border, various media reported.
On Saturday, rumours spread that Germany would take in thousands of those seeking refuge from the camp, prompting police to announce over loudspeakers in Arabic and Farsi that the rumours were not true and that the border would not be opened, according to eyewitnesses.
In a report published Friday, German leftist politician Bodo Ramelow told news magazine Der Spiegel that his state of Thuringia could take in 1,000 to 2,000 refugees from the Idomeni camp with the coordinated effort of other German states.
It remains unclear if the rumour spread at Idomeni originated with this report.
Earlier on Sunday, Greek security forces said they arrested nine suspected people smugglers on the island of Kos.
The security forces seized forged documents supposedly from the Greek authorities and machines that could be used to forge personal documents.
"The people arrested are foreigners and are according to all indications members of a human-trafficking gang that is bringing migrants from Turkey to Greece and thereby into the EU," an officer from the Greek coastguard told dpa.
Since the implementation of a migration deal between the EU and Ankara on March 20, Greece has seen consistently fewer migrants arriving on its shores from Turkey, with the Greek crisis committee saying Sunday that only 73 people arrived in the past 24 hours.
Under the deal, all migrants arriving in the Greek islands from March 20 who do not qualify for asylum will be returned to Turkey.