The Chinese territory has had its borders effectively sealed since 2020 with few flights able to land and passengers banned from transitting.
"This is not the time to lift the ban. A lot of people will rush to come back...there will be infected cases and that will add a lot of pressure to our public hospital system," Lam said.
Her comments come a day after she announced a shift in her government's approach to tackling the coronavirus, devoting more medical resources to elderly people as infections and deaths climb rapidly amongst the city's mainly unvaccinated seniors.
Hong Kong's government had previously focused its resources on identifying, treating and isolating all cases, even those that are asymptomatic and mild, adding pressure on its hospitals and healthcare system.