The countries were added to the list of coronavirus-affected countries in light of the deteriorating epidemiological situation there.
"Persons arriving from or via the affected countries are required to self-isolate," the ministry said in a press release.
According to the decree signed by Health Minister Aurelijus Veryga on Monday, Denmark's coronavirus infection rate has reached more than 25 cases per 100,000 inhabitants over the last 14 days.
The rate ranges between 16 and 25 cases in Ireland, Greece, the United Kingdom and Nepal.
Foreign travelers from countries with over 25 cases per 100,000 must present proof of a negative COVID-19 test carried out within 72 hours before their arrival in Lithuania.
Lithuanian nationals returning from such countries have to get tested within 24 hours of returning to the country.
All travelers arriving in Lithuania by air or sea must register with the National Public Health Center (NPHC) by filling out a paper or online form before they leave the airport or seaport.
Travelers coming by land must do so within 12 hours upon arrival.
A country or a territory is added to the list if its COVID-19 incidence rate exceeds 16 cases per 100,000 inhabitants over the last 14 days. Austria, Croatia, Poland and Turkey are among the countries on the list.