"Stay the course, the situation is serious. Once again, I would like to ask for a real effort," Prime Minister Stefan Lofven said.
He urged inhabitants to limit their social contacts and avoid large private gatherings over Easter.
The government acted on advice from the Swedish Public Health Agency.
Municipalities were urged to keep non-essential activities closed, including swimming pools and sports centres, until April 18.
Restaurants and cafes will still have to close at 8:30 pm, regardless of whether they sell alcohol or not. This was extended to May 3.
A limit of 500 people was to remain in place for shopping centres.
Initially, some easing of restrictions was planned to start on 11 April. The Public Health Agency on Tuesday said in a memorandum to the government that it would be preferable to wait until 3 May - provided caseloads drop sufficiently.
The number of infections is rising in most parts of the country, presenting an additional burden on the health system, the authority cautioned.
The country of 10.3 million has recorded more than 904,000 cases and more than 13,465 virus-related deaths since the pandemic began.
Sweden adopted a more lenient coronavirus strategy at the start of the pandemic, but it has gradually tightened its measures.