Donald J. Trump left little doubt on Monday that he intends to run on the same proposals on immigration and terrorism that animated his primary campaign, using his first speech after the massacre in Orlando, Fla., to propose sweeping measures against Muslims that pay little heed to American traditions of pluralism.

Without distinguishing between mainstream Muslims and Islamist terrorists, Mr. Trump suggested that all Muslim immigrants posed potential threats to America’s security and called for a ban on migrants from any part of the world with “a proven history of terrorism” against the United States or its allies. He also insinuated that American Muslims were all but complicit in acts of domestic terrorism for failing to report attacks in advance, asserting without evidence that they had warnings of shootings like the one in Orlando.

Mr. Trump’s speech, delivered at St. Anselm College in Manchester, N.H., represented an extraordinary break from the longstanding rhetorical norms of American presidential nominees. But if his language more closely resembled a European nationalist’s than a mainstream Republican’s, he was wagering that voters are stirred more by their fears of Islamic terrorism than any concerns they may have about his flouting traditions of tolerance and respect for religious diversity.