Polish interior minister said on Friday Europe faces a “clash of civilizations” after a van had ploughed into crowds in Barcelona, Spain, Radio Poland reported.
ISIS terror group has claimed responsibility for the attack.
A regional official said 13 people were killed, while police said they were treating the incident as a terrorist attack, the Reuters news agency reported.
Around 100 people were taken to hospital with injuries, and 15 were in a serious condition, Polish media reported, citing local authorities.
There were no reports late on Thursday of Poles being among the victims.
Interior Minister Mariusz B?aszczak told state broadcaster TVP Info that Poland is a safe country, adding: "In Poland we do not have Muslim communities which are enclaves... which are a natural support base for Islamic terrorists."
“Europe should wake up,” he added.
B?aszczak said that resettling migrants encourages millions of people to come to Europe.
“This ends tragically. We are dealing with a clash of civilizations. This must be said outright and it is a problem for the whole of Europe," he added.
Poland has refused to take part in an EU plan to resettle African and Middle Eastern migrants from camps in Italy and Greece, arguing that the programme did not solve the problem at its origin, and was a threat to security.
B?aszczak said on Thursday: "We will not succumb to this pressure [from the European Commission] , because this is about the security of Poland and Poles."
He added that Polish officials were "in constant touch" with Spanish authorities.
Eyewitnesses reported that a van zigzagged at speed down Las Ramblas, a busy avenue in Barcelona popular with tourists, ploughing into pedestrians on Thursday afternoon.
The head of the Spanish region of Catalonia said two people had been arrested. It was still not clear how many attackers had been involved.