A 16-year-old Roma boy is in critical condition after being shot in the head by police near Thessaloniki.
Greece’s government has called for calm after the second night of unrest following the police shooting of a Roma teenager.
Protesters in the industrial Athens region of Aspropyrgos allegedly torched a local tyre business and a bus on Wednesday, setting up barricades in the streets.
Roadblocks were also in the area of Chalkidona, about 40 kilometres west of the country’s second-largest city, Thessaloniki.
Authorities have issued a warning to residents of Aspropyrgos to remain indoors with windows and doors closed.
"I would like to ask for calm and prudence from all, but also to state clearly that there will not be the slightest tolerance of aggressive, illegal, violent behaviour toward law enforcement officers,” government spokesman Giannis Oikonomou said during a regular press briefing on Thursday.
Protests broke out after a 16-year-old boy was shot in the head following a police chase near Thessaloniki.
Authorities had been pursuing the teenager after he failed to pay a bill of €20 at a petrol station. The boy remains in a critical condition in hospital.
The 34-year-old police officer who fired the shot has been suspended and is due to appear in court Friday for questioning on charges of manslaughter with possible intent and illegally firing his weapon.
Greek police say the teenager had tried to ram an officer's motorbike during the chase with his pickup truck.
Oikonomou has described as a “tragic incident” and said the matter was being fully investigated.
"This does not in any way excuse acts of violence and lawlessness being carried out by those who want to protest," he told reporters.
But the president of the Panhellenic Roma Confederation has denounced the "racist" culture of Greek authorities towards the minority.
"This is a tragic incident, the fourth of its kind in a year in our community," Vassilis Pantzos told AFP, adding that the majority of Greek Roma suffer from "exclusion and live in misery".
There are between 170,000 and 300,000 Roma people in the country.