Macedonian police fired tear gas on Wednesday to disperse around 50 migrants stranded in Greece who tried to pull down part of the razor wire fence separating the two countries, a Reuters witness said.
Scuffles briefly broke out and Greek riot police later intervened to break up the crowd.
Tensions have boiled over at the makeshift migrant camp near the town of Idomeni, where more than 10,000 migrants and refugees have been stranded since February, when Balkan countries shut their borders to anyone wanting to head north.
Hundreds of migrants were injured on Sunday in clashes with Macedonian police, who fired tear gas and rubber bullets after a group tried to storm the border.
The Balkan route was the preferred gateway into western and northern Europe last year for around 1 million migrants from the Middle East and beyond.
Macedonian President Gjorge Ivanov and his Slovenian and Croatian counterparts, Borut Pahor and Kolinda Grabar-Kitarovic, later on Wednesday visited a migrant transit centre just inside Macedonia, which houses 135 migrants trapped by the border closures.
After meeting some of the Croatian and Slovenian police who are helping to guard the Macedonian border, Ivanov said his country's authorities would keep the migrant route closed in line with EU policies.
"The latest incidents on the border showed there is a great pressure from the migrants to re-open this corridor, but ... we will respect that decision," he told reporters.