Washington (CNN) -- President Barack Obama said Friday that all options for responding to the crisis in Libya remain on the table, but he added that any military option means that "you've got to balance costs versus benefits, and I don't take that decision lightly."
Obama told reporters the desired outcome would be for Libyan leader Moammar Gadhafi to "step down" in the wake of civil war that has erupted in the North African country and Gadhafi's military attacks on his own people.
His comments followed a call by European Union leaders earlier Friday for Gadhafi to "relinquish power immediately," and France's embrace of the Libyan opposition leadership.
The U.S. Treasury Department on Friday added nine more Libyans, including Gadhafi's wife and several more of his children, to a list that freezes their assets in the United States and restricts their dealings with U.S. entities. Gadhafi and some of his other sons already were on the list.
At a White House news conference, Obama outlined steps the United States has taken so far to pressure Gadhafi to step down, including the previously announced sanctions as well as talks with NATO allies on the possibility of establishing a no-fly zone over Libya.
He noted that Secretary of State Hillary Clinton would meet with Libyan opposition figures in coming days during a trip to Egypt and Tunisia, and that his government has assigned "a representative whose specific job is to interact with the opposition and determine ways that we can further help them."
However, Libya's former U.S. ambassador, who resigned last month in protest of Gadhafi's violence against protesters, called Friday for the United States to recognize the newly created opposition National Transitional Council he now represents.
"We want recognition from all the rest of the world for this council," Ali Aujali told Libyan-American supporters and reporters.
The French government on Thursday recognized the opposition council as the sole representative of the country, and the British foreign secretary spoke to an opposition representative over the phone.
German Chancellor Angela Merkel was more cautious, calling the Libyan council a possible interlocutor.
Clinton told a House committee Thursday that Washington was "suspending" its ties to the Libyan Embassy and reaching out to opposition leaders "inside and outside of Libya."
The move effectively orders the embassy to close, though it stops short of breaking U.S.-Libyan diplomatic relations, a senior administration official told CNN.
Aujali abandoned Gadhafi last month, and the United States has not recognized his replacement, the official said.
Obama has been criticized by Republicans and some Democrats for not ordering a no-fly zone over Libya or other steps intended to prevent Gadhafi from using military force against his own people.
Both Obama and Clinton have said any U.S. military involvement must be part of an international effort, preferably sanctioned by the United Nations and Arab governments. Obama said Friday that NATO officials will meet next week to consider creating a no-fly zone over Libya.
On Thursday, White House National Security Adviser Thomas Donilon said the U.S. government planned to send "purely humanitarian" disaster relief teams into eastern Libya, where rebels battling Gadhafi were losing ground.
The U.S. Agency for International Development teams will be sent into monitor the delivery of humanitarian aid and should not be viewed as a military operation, he said.