“The main thing that I’ve been trying to communicate over the last several of these horrific episodes is that, contrary to popular belief, Americans are not more violent than people in other developed countries,” Mr. Obama said. “But they have more deadly weapons to act out their rage.”

Asked by interviewer Bill Simmons of HBO if gun control will be the “dominant” issue on his agenda next year, Mr. Obama replied, “I hope so.”

“We have this weird habit in this culture of mourning and, you know, 48, 72 hours of wall-to-wall coverage, and then … suddenly we move on,” Mr. Obama said. “And I will do everything I can to make sure that there’s a sustained attention paid to this thing.”