It warned people via social media about problems accessing electricity amid a heatwave.
The heatwave was likely contributing to power shortages in areas such as Split, Šibenik, Omiš, Makarska, Dubrovnik, Zadar and the surrounding islands, according to officials.
"Due to the power outage, traffic lights are not working, causing traffic disruptions," the Polish embassy in Croatia said.
"Please follow local service announcements and exercise caution," it added.
Blackouts have been reported in Croatia, Bosnia and Herzegovina and Montenegro.
Electrical and Wi-Fi networks in Montenegro stopped functioning around 1 p.m. local time, according to a report by the Reuters news agency.
Power disruptions also occurred in Bosnia, Albania and most of Croatia's coast.
In Bosnia's capital Sarajevo and cities such as Banja Luka and Mostar, some areas experienced halted traffic when temperatures exceeded 40 degrees Celsius, Reuters reported.
Montenegro's energy minister confirmed that the power outage was caused by a sudden increase in energy consumption due to the heatwave.
(mp/gs)