He added that evacuations have been organised in coordination with Moscow with "reception and accommodation facilities for our citizens are ready in the Rostov region".
A Ukrainian separatist leader has called on residents to flee to Russia amid the tense military standoff between Ukraine and Moscow.
Denis Pushilin, the head of the self-proclaimed Donetsk People's Republic (DPR), said in a statement that the Ukrainian army planned to "seize the Donbas by force" and that civilians needed to be evacuated.
He accused Ukrainian forces of having amassed "troops and lethal weapons" along the line of contact and claimed that the army is now "in combat formation and ready".
"The lives and health of our citizens may be endangered if the enemy shells populated areas of the republic.
"For this reason, as from today, 18 February, a mass centralised evacuation of the population to the Russian Federation has been organised," he stated.
He added that evacuations have been organised in coordination with Moscow with "reception and accommodation facilities for our citizens ready in the Rostov region".
"All conditions have been created for a quick transition at the checkpoints," he continued.
Women, children and the elderly are to be the first to be evacuated.
Russia-backed separatists, who control parts of eastern Ukraine since the conflict erupted in 2014, and Ukrainian authorities have accused each other of bombings which Western allies have said could be used as a pretext by Russia to invade its neighbour.
Moscow has deployed about 150,000 troops along its border with Ukraine and in neighbouring Belarus in recent weeks but insists it has no intention to invade.
It has demanded, however, that NATO guarantees Ukraine will never be allowed to join the security alliance. It has also requested the alliance withdraw some troops and weapons for several countries in eastern Ukraine, arguing they threaten its own security.
Moscow announced that it had begun to pull back troops from the border but the West has questioned this claim, affirming that thousands more troops have actually been deployed.
Both sides have accused each other of "disinformation".
Russian President Vladimir Putin and his security council on Friday discussed the situation and "the growing tensions that are being provoked by external forces," the Kremlin said in a statement.
The Kremlin also announced on Friday that its military will carry out massive drills of its strategic nuclear forces on Saturday that will be overseen by Putin.
US Secretary of State Antony Blinken revealed some conclusions of US intelligence in Thursday's speech at the UN Security Council, warning that Russia could create a false pretext for an invasion with a “so-called terrorist bombing” inside Russia, a staged drone strike, “a fake, even a real attack … using chemical weapons.”
He charged that invasion would open with cyberattacks, along with missile strikes and bombs across Ukraine, describing the entry of Russian troops and their advance on Kyiv, a city of nearly 3 million, and other key targets.
Despite the stark US warnings, Ukrainian officials sought to project calm, with Oleksii Danilov, head of the National Security and Defense Council, saying late Thursday that there were no signs a massive Russian invasion was imminent.