Ethnic Albanians make up about one-quarter of Macedonia's 2.1 million people. Relations between the country’s Macedonians - who are Orthodox Christians - and ethnic Albanians - who are mostly Muslim - have long been fraught.
Macedonian President Gjorge Ivanov vetoed Wednesday a law giving greater status to the Albanian language in the Balkan country, saying it could endanger its "unity and sovereignty".
Conservative Ivanov said that the law would block and make state administration dysfunctional "risking jeopardising unity, sovereignty and territorial integrity of the Republic of Macedonia."
"We are passing an unjust law that favours only Albanian language," Ivanov told reporters, adding that it was not in line with the constitution.
"Therefore... I decided not to sign the law into effect."
However, the bill will be sent back to the parliament for a new vote and if it is approved again the president has to sign it.
Macedonian government regretted the decision in a statement, saying the law was "in line with the constitution" and motivated by the "care for all citizens of Macedonia."
Ethnic Albanians make up around a quarter of Macedonia's two million people, and Albanian has until now been an official language only in areas where the minority makes up certain numbers.
Macedonian is the primary language used in the predominantly Slavic country.
The new law, passed last week by the Social-Democrats-led ruling coalition in parliament, anticipates that ethnic Albanians can request nationwide that their language be used in their administrative, health, judicial, police and other such official matters.
In parliament, it can be used by their elected representatives.
The adoption of the law was a demand of Macedonia's ethnic Albanian parties before they agreed to join a ruling coalition with the Social Democrats last year.
The deal ousted the nationalist rightwing VMRO-DPMNE party, in power since 2006.
Ivanov, who is close to now opposition VMRO-DPMNE, echoed their claims that the new law risks breaking up the fragile ex-Yugoslav republic.
In 2001 ethnic Albanian rebels waged an insurgency against Macedonian authorities, which left more than 100 people dead and ended with an agreement providing greater rights for the minority.