"We must also be prepared for Russia might disconnect Estonia, Latvia, and Lithuania from their electricity grid", she said in a televised address on Thursday evening.
"It would be wise to be prepared for possible power outages – that includes public authorities, companies, and every individual", she added, describing any disruptions as "temporary".
Almost 3,000 reservists were called to an annual week-long defence exercise "Okas" in Estonia on Thursday, although Kallas said there is no immediate military threat to the country.
Baltic states are scheduled to disconnect from shared Russian powergrid in 2025 in favour of the decentralised power system of continental Europe.
