President Poroshenko said the authorities needed firm power in case of a full-scale Russian invasion/EPA
Ukraine has declared martial law in part of the country after Sunday's capture of three of its naval vessels and 23 crew members by Russia.
Lawmakers backed President Petro Poroshenko's request to introduce it in regions mostly bordering Russia for 30 days starting from 28 November.
The authorities can now restrict public rallies and regulate the media, reports BBC.
Some MPs expressed fears Mr Poroshenko could suspend a presidential poll on 31 March 2019 - a claim he firmly denied.
Sunday's naval clash was off the coast of Crimea, annexed by Russia in 2014. Russian coastguard ships opened fire before special forces stormed the Ukrainian vessels. Between three and six Ukrainians were injured.
Ukraine said it was a Russian "act of aggression". Moscow said the ships had illegally entered its waters.
The naval clash is the first time Russia and Ukraine have come into open conflict in recent years, although Ukrainian forces have been fighting Russian-backed separatists and Russian "volunteers" in the east since 2014.