The Council on American-Islamic Relations, a Muslim advocacy group, said it "condemned" Thursday's terror attack in Barcelona, Spain, which left 13 dead and hundreds injured, as well as President Trump's tweets in response to the attack.

"We condemn the terror attack in Barcelona, and we condemn President Trump's irresponsible and Islamophobic response to that attack. President Trump claims he needed days to get the 'facts' on Charlottesville, and said nothing about the recent bombing of a Minnesota mosque, but tweeted false information within minutes of the Barcelona attack," CAIR Executive Director Nihad Awad said.

Awad added that Trump's invocation of the "widely debunked myth about U.S. Gen. John Pershing in the Philippines ... may just be his attempt to divert attention from widespread criticism of his response to the domestic terror attack in Charlottesville."

"Study what General Pershing of the United States did to terrorists when caught. There was no more Radical Islamic Terror for 35 years!" Trump tweeted Thursday following the attack. He later tweeted to that Spain should be "tough and strong." The Islamic State claimed credit for the attacks in the tourist destination of Las Ramblas in Barcelona.

Trump did not clarify what he meant by what General Jack Pershing did to terrorists, but in the past he has repeated a claim that Pershing, while fighting the Moro uprising in Philippines in the early 1900s, shot prisoners with bullets "dipped ... in pig's blood." Pigs are unholy to Muslims. That claim about Pershing appears to be false, according to historians. However, the general did use other tactics to dissuade Muslim insurgents. According to a 2009 biography, Pershing wrote in an unpublished memoir that "the bodies [of insurgents] were publicly buried in the same grave with a dead pig" and that this "materially reduced in number" the attacks.