"I spoke last night on the telephone with Bulgarian Prime Minister Boyko Borisov who travels today to Turkey. Greece and Bulgaria are currently the most engaged in controlling their borders with Turkey," Plenkovic said, adding that the crisis at Idlib, Syria, had generated a new potential migrant wave.
"We have been consulting with all colleagues in the EU and NATO," he said.
Erdogan said on Saturday that Turkey had opened its borders for migrants and that 18,000 were already on their way to Europe.
The EU has relied on Turkey to stop the migrant wave after since 2015 more than one million people arrived in Europe from the Middle East, triggering a political crisis in Europe.
Plenkovic believes that "political and diplomatic efforts should be undertaken towards President Erdogan to avert a more serious migration wave towards Europe via the eastern Mediterranean and Western Balkan routes."
He said that Croatia had so far been investing significant effort into controlling the external EU border, "and not only as part of its preparations for the Schengen area", and that 6,500 police officers had been engaged and €271 million absorbed from EU funds "to enhance (border protection) capacity and buy technical equipment, thermal cameras and other equipment police officers are expected to have."