Rajapaksa is scheduled to chair a meeting with members of the presidential task force on the coronavirus before his address to the nation on Friday evening.
Many restrictions are already in place, with schools, gyms and swimming pools closed, and weddings and musical shows banned.
Authorities also imposed a night curfew from Monday, restricting movement from 10pm until 4am every day.
Around a quarter of Sri Lanka’s population has been fully vaccinated, a majority of them with China’s Sinopharm vaccine.
Sri Lanka has also approved the Pfizer-BioNTech, Moderna , AstraZeneca and Sputnik V shots.
The country has reported a total of 372,079 infections since the start of the pandemic last year, with 6,604 deaths.