BUCHAREST, Romania — Romania's president has canceled a visit to Ukraine next month to protest a law that critics say would infringe on the rights of ethnic minorities there.

In remarks late Thursday in New York where he is attending the United Nations General Assembly, President Klaus Iohannis said his announcement was "an extremely ... tough diplomatic signal."

Iohannis also said he had called off an imminent visit to Bucharest by Ukrainian President Petro Poroshenko.

Iohannis said he was "very, very unpleasantly surprised" by the vote in the Ukrainian parliament.

The law, approved Sept. 5, restructures Ukraine's education system and specifies that Ukrainian will be the main language used in schools. Ukrainian officials have rejected the suggestion that minority languages will be sidelined.

"If this law comes into effect, it will drastically limit the access of minorities to education in their mother tongue," he said. "This hurts us because there are a lot of Romanians in Ukraine."

In a 2001 census, there were an estimated 400,000 Romanian speakers in Ukraine, of which 250,000 declare themselves Moldovan and 150,000 say they are Romanian.

Russia, Hungary and Moldova have also expressed concern about the law.