The condemnation came as reports from Spain said the dead and injured Barcelona included nationals from countries like Pakistan.
The Pakistan government condemns, "in the strongest possible terms", the terrorist attack in Barcelona, the Foreign Office said.
It said Pakistan would like to convey profound sympathies for the families and friends of the victims.
The Foreign Office, however, said it has not received any information about Pakistani citizens being among the dead or injured. "Our missions in Madrid and Barcelona have set up situation rooms, which will continue to operate until required," it said.