WASHINGTON — The U.S. renewed efforts today to evacuate American citizens from Libya, this time by ferry, as concerns rise about longtime leader Moammar Gadhafi’s unpredictable behavior.

As security forces unleashed a bloody crackdown on protesters demanding Gadhafi’s ouster, Secretary of State Hillary Rodham Clinton called the violence “completely unacceptable.”

But as it sought to safely extricate U.S. diplomats and other Americans from the spreading chaos, the Obama administration stopped short of criticizing Gadhafi personally or demanding that he step down.

Unease over the safety of U.S. citizens intensified after attempts to get some out on Monday and Tuesday were unsuccessful. Late Tuesday, the State Department announced that American citizens would be evacuated from Libya by ferry to the Mediterranean island of Malta.

This morning, officials were processing U.S. citizens for the ferry trip from Tripoli’s As-shahab port.

Department spokesman P.J. Crowley said U.S. officials had been assured by Libyan authorities that embassy workers and families will be able to leave safely. He said the United States expects those pledges to be honored.