"The regulation on the extreme situation will be amended to expand the list of requirements for wearing masks indoors," she told reporters.
The Cabinet will discuss the issue on Wednesday if the necessary documents are ready by that time, according to Simonyte.
The prime minister also confirmed that the government was not planning any further changes, such as imposing new rules for events, for now.
Currently, wearing facemasks is recommended but not mandatory for those who have the COVID-19 immunity certificate.
It was said earlier that a lockdown might have to be reintroduced in Lithuania to make face coverings mandatory again.
Last week, Lithuania moved into the worst "black" zone under the color-based pandemic classification system.
The latest official statistics showed on Tuesday that the country's 14-day coronavirus infection rate had risen to 634.7 cases per 100,000 people.