Up to 2.5 million Crimeans were left without electricity over the weekend when explosions downed several transmission towers in southern Ukraine, according to Russia's Emergencies Ministry.
"If Ukraine does not restore Crimea’s power supply, we will be forced to respond with adequate measures. Such measures are being developed," Matvienko told reporters.
"This is not provocation, this is a terrorist act," she stressed.
A state of emergency has been declared in the Black Sea peninsula following the blackout, switching to local emergency power generators.
Supporters of the Crimean energy blockade are continuing to prevent police and repair crew access to the damaged electrical facilities.