Secretary of State Hillary Rodham Clinton, CIA Director Leon Panetta and other national security "principals" were meeting in the White House situation room to discuss administration options for Libya.
"I don't want to raise expectations that this is a meeting that will lead to imminent, concrete action," Carney said.
Pressure to act has increased amid reports that forces loyal to dictator Moammar Gadhafi are gaining the upper hand on rebels -- thanks in part to aerial bombardment of rebel-held cities that has claimed an unknown number of civilian lives. Both Republicans and more hawkish Democrats have been calling on the White House to follow up on Obama's comments Monday that he is considering military options.
But in an interview on CBS, Clinton noted that the British and French planned to introduce a draft U.N. Security Council resolution authorizing international action, and said, "We think it's very important that there be a U.N. decision on whatever might be done."
She added: "There is still a lot of opposition, as you probably know, within the Security Council."
Asked later if the administration would consider joining an effort to enforce a no-fly zone without a U.N. imprimatur, Carney declined to give a clear answer. Instead, he repeatedly said that "it is our strong preference that the action we take be done with our international partners" and that it's important to work with the U.N.
Russia and China, both permanent Security Council members that wield a veto, have suggested they are likely to oppose approval of a no-fly zone.
The possibility of a decision by NATO countries to step in without a U.N. resolution also appeared increasingly unlikely, in part because NATO member Turkey has suggested it won't back such an effort. Major NATO decisions require a unanimous vote by the alliance's member states.
Defense Secretary Robert Gates arrived in Brussels late today to discuss Libya with fellow NATO defense ministers this week, but there was no indication he expected to leave with a new plan.
Both Clinton and Carney suggested the administration fears how solely Western intervention might be perceived in the Arab world.
Sounding a bit on the defensive, Carney noted the administration has already enacted financial sanctions against Gadhafi's regime, coordinated humanitarian efforts for refugees fleeing the fighting and positioned Navy ships and other resources in the region as it plans for military contingencies.
But he suggested the world shouldn't hold its breath for the next step.
"The actions we have taken have been dramatic," he said, "and we are implementing them in a way we hope will have an effect."