WASHINGTON — President Barack Obama demanded Friday that Moammar Gadhafi halt all military attacks on civilians, and he said that if the Libyan leader did not stand down the United States would join other nations in launching military action against him.

But the president also stressed the United States “is not going to deploy ground troops into Libya.”

In a brief appearance at the White House, Obama said Secretary of State Hillary Rodham Clinton would travel to Paris on Saturday to join allies in discussing next steps in Libya, where Gadhafi has pressed a brutal crackdown against rebels trying to end his 42-year reign.

Stressing that the United States was acting in concert with European allies and Arab nations, the president said, “Our goal is focused, our cause is just and our coalition is strong.”

Obama’s remarks came less than 24 hours after the United Nations Security Council voted to authorize military action — including a “no-fly zone” over Libya — to prevent the killing of civilians by Gadhafi’s forces.