The president spoke shortly before convening a meeting of his national security advisers on a range of Pentagon options for confronting the Islamic State group.
However, he said his strategy would require more than military action and called for a regional strategy that includes political support from other countries in the region.
In blunt terms, the president said it was time for Middle Eastern nations to “stop being ambivalent” about the aims of extremist groups like the Islamic State.
“They have no ideology beyond violence and chaos and the slaughter of innocent people,” Obama said, alluding to the group’s announcement last week that it had killed American journalist James Foley.
The militants also have threatened to kill other U.S. hostages.
The U.S. already is striking Islamic State targets in Iraq, and officials have said the president is considering similar action in neighboring Syria in the wake of Foley’s death. The militants have moved with ease between the two countries, effectively blurring the border.
However, the president said Thursday that his top priority remains rolling back the militants’ gains in Iraq, where he has said they pose a threat to U.S. personnel in Erbil and Baghdad.
Obama said that if he were to expand that military mission, he would consult with members of Congress, who are due to return to Washington in early September.
“The suggestion has been that we’ll start moving forward imminently and somehow Congress, still out of town, will be left in the dark,” Obama said. “That’s not what’s going to happen.”