Cuban President Miguel Díaz-Canel has warned the country to expect problems with fuel supplies in the coming weeks.
He said the distribution, especially of diesel, was being badly affected by US sanctions against Venezuela - Cuba's principal oil supplier.
He said it was likely there would be blackouts next week, suggesting that people should work from home.
Mr Díaz-Canel said Cuba was in a better position than in the 1990s - the years of extreme austerity and blackouts.
That time - known as the Special Period - followed the collapse of the Soviet Union, a key donor of the Communist-run island.
In 2017, US President Donald Trump reimposed some trade and travel restrictions lifted by his predecessor Barack Obama, although he kept the embassy open in Havana and did not end flights to the country.
What did Miguel Díaz-Canel say?
In an unexpected appearance on television on Wednesday, the Cuban president warned the government must implement emergency measures to stave off an acute fuel shortage.
But he admitted that "there may be tense situations in the distribution of some products and the provision of services to the population in the coming days".
Specifically, he guaranteed that there would be no blackouts before Sunday - but not after that.
The president added that possible blackouts "will not be as long nor as intense of those of the Special Period".
However, it is clear that there will need to be more belt-tightening measures ahead, possibly rationing fuel if things do not stabilise in the coming weeks, the BBC's Will Grant in Havana reports.
What's the background to this?
Cubans have been down these roads in the past, and talk of austerity brings back bad memories for many on the island, our correspondent says.
A universal rationing system was introduced on the island just after the revolution in 1959.
In April, 91-year-old Cuban revolutionary Guillermo García Frías suggested Cubans could eat ostriches, crocodile and edible rodents known as jutía amid the shortages, prompting a flood of memes mocking the commander's suggestion.
Some in Cuba had hoped the recent resignation of US National Security Adviser John Bolton - renowned for his anti-Castro policies - might usher in an improvement in bilateral ties.
However, the Trump administration has shown no intention of easing up on the sanctions or the efforts to prevent tankers of fuel from Venezuela making their way to Cuba.