French President Emmanuel Macron is due to meet the leaders of Slovakia and the Czech Republic on October 26.
As he kicked off his trip, Macron warned eastern EU members not to fall out of step with the bloc's principles, singling out Hungary and Poland, whose nationalist governments have clashed with Brussels.
In an interview published in Czech, Hungarian, Polish, and Slovak media, the French leader insisted that "Europe is not a supermarket," stressing a point he made previously that eastern states could not pick and choose among the bloc's fundamental values.
"Europe isn't a one-way street: it is a reciprocal commitment," Macron said in the interview.
He expressed concern about the refusal of some eastern EU members to accept migrants from the Middle East and North Africa under an EU quota program drafted in the wake of the 2015 migrant crisis.
"We have a collective need for coherence and solidarity: we cannot benefit from the European budget without demonstrating solidarity on migration," Macron said.
The French president is expected to hold talks in Bratislava with Slovak President Andrej Kiska and Prime Minister Peter Pellegrini.
Macron is due later on October 26 in Prague as the Czech Republic celebrates the centenary of Czechoslovakia gaining independence from the Austro-Hungarian Empire at the end of World War I.
Macron plans to meet Czech President Milos Zeman and Prime Minister Andrej Babis before leaving for a summit on Syria in Istanbul.