Three hospitals in Belgrade, after a break of just a month, have been transformed back into coronavirus-only facilities.
It comes after the country recorded its highest increase in infections since April.
Restrictions have also been tightened in Kosovo.
On Monday the government impose a 9 am - 5 pm curfew in the capital Pristina and three other cities. Authorities have also told businesses to reduce their staff to the minimum, and restaurants and cafe are serving in open spaces only.
Prime Minister Avdullah Hoti said he won't hesitate to declare a state of emergency if the situation requires it.
Last week Austria said it was imposing a travel warning for six western Balkans countries, Bosnia, Kosovo, North Macedonia, Albania, Montenegro and Serbia, in view of high COVID-19 figures.
Spain and Germany keep confinement measures to battle local outbreaks
Spain, one of Europe's worst-affected countries, has put some 270,000 people back into lockdown within two days after a spike in cases in the northern regions of Galicia and Catalonia.
In Germany, a country that has been battling new outbreaks too, the health minister resisted on Monday calls to drop rules requiring people to wear masks in shops, a request coming from Mecklenburg-Western Pomerania - the German state least affected by COVID-19.
Also in Germany, MTU Aero Engines announced on Monday it plans to cut staffing by 10-15% by the end of next year, adding up to the long list of companies, many of which in the aviation sector, which had to slash their workforce because of the pandemic.