The withdrawal of the tanks from Misrata was a rare success for the rebels. The disorganized opposition holds much of the east but has struggled to take advantage of the gains from the international air campaign, which appears to have hobbled Gadhafi's air defenses and artillery just as the rebels were facing defeat.
Gadhafi was defiant in his first appearance in a week. Libyan TV broadcast what it said was a live speech outside Gadhafi's compound.
"In the short term, we'll beat them, in the long term, we'll beat them," he said.
But President Barack Obama, who is wrapping up a South American tour, said the no-fly zone enforcement is working.
The strikes are costing the U.S., which now wants to take a step back and let NATO take the lead on the operation.
"When this transition takes place, it is not going to be our planes that are maintaining the no-fly zone," Obama said. "It is not going to be our ships that are necessarily enforcing the arms embargo. That's precisely what the other nations are going to do."
NATO warships have started patrolling off Libya's coast to enforce the U.N. arms embargo, as the alliance appeared set to assume responsibility for the no-fly zone over Libya to protect civilians.
The Associated Press contributed to this report.