The Trump administration is preparing to ask Cuba to cut its embassy staff in Washington by 60%, according to officials.
They continued that the State Department is expected to announce the decision on Tuesday.
The officials added that the intention was not to punish Cuba, but to ensure both countries have a similar number of diplomats in each other's capitals.
Cuban diplomats will not be formally expelled from Washington unless Havana refuses to send them home.
Last week the United States told 60% of its diplomatic staff in Cuba to withdraw and American travellers were warned not to visit the country following "specific attacks" against US diplomats.
All non-essential staff at the embassy in Havana were last week told to leave, along with their families.
The US said it would only keep "emergency personnel" in the country after a number of diplomats in Cuba believe they have been the victims of sonic attacks since the end of 2016.
Roughly 50 Americans had been working at the embassy.
At least 21 diplomats and family members have been affected by the ailment which resulted in hearing loss, concussions, nausea, headaches and ear-ringing, as well as issues with concentration and common word recall.
The Trump administration has pointedly not blamed Cuba for the attacks, and officials have spent weeks weighing how to minimise the risk for Americans in Cuba without harming relations with the country or falling into an adversary's trap.
Some investigators have suggested the attacks could have been committed by an outside power such as Russia or Venezuela to drive a wedge between the US and Cuba.
The FBI and other agencies searched homes and hotels where incidents have occurred but found nothing to link to the ailments.
Secretary of State Rex Tillerson, who reviewed options for a response with president Trump, said: "Until the government of Cuba can ensure the safety of our diplomats in Cuba, our embassy will be reduced to emergency personnel in order to minimise the number of diplomats at risk of exposure to harm."
Americans have also been warned to stay away from the Caribbean country, a decision that could hit Cuba's economy that has expanded in recent years as the US relaxed restrictions.