A four-story building in Libyan leader Moammar Gadhafi's Tripoli compound has been heavily damaged, possibly by cruise missiles, CNN's Nic Robertson reported.

Robertson, invited by government officials to see the damage, said early Monday local time that two circular holes in the building may be telltale signs of cruise missiles, although that could not be immediately confirmed.

The leader's whereabouts were not known.

The building is only 100 yards or so from a statue of a golden fist crushing a model plane emblazoned with "USA" -- a monument to the 1986 American bombing of Libya, in which one U.S. plane was downed.

U.S. officials earlier Sunday said they are not targeting the leader, who has defied international calls to stop attacking opposition forces.

The United States, detailing significant damage to Gadhafi's air defenses and a military convoy, also fought a public relations campaign Sunday, insisting that coalition bombing wasn't going beyond mandates in the United Nations Security Council resolution.

Secretary of Defense Robert Gates warned against widening the current allied operations to include a direct attack on Gadhafi.

Anything that goes beyond enforcement of the no-fly zone and prevention of new military attacks on rebels risks disrupting the "very diverse coalition" that agreed to the attacks, said Gates, adding there was unanimous agreement in the top echelons of the Obama administration to push forward with military action in Libya.

Gates said the operation is off to "a strong and successful start."

He made the comments while traveling to Russia, which said earlier Sunday that innocent civilians were being killed and urged more caution. The Foreign Ministry in Moscow cited reports that "nonmilitary" targets were being bombed, including a cardiac center.

"We have no indication of any civilian casualties," U.S. Navy Vice Adm. Bill Gortney said at a Pentagon press briefing.

The Libyan military on Sunday called an immediate cease-fire after allied forces pounded one of its convoys near Benghazi and, according to U.S. officials, significantly degraded the regime's air defenses.

National Security Adviser Tom Donilon scoffed at the report of the cease-fire, saying, "It isn't true or it was immediately violated."

"We are not going after Gadhafi," Gortney said at a Pentagon press briefing. "Regime forces are more pressed and less free to maneuver."

Asked about reports of smoke rising from the area of Gadhafi's palace, Gortney said, "We are not targeting his residence."

Despite Libyan government contentions that women, children and clerics have died in allied attacks, Gortney and other officials said that's not the case.

President Barack Obama and his national security team worked behind the scenes to shore up support within the Arab world for the military mission in Libya, according to senior administration officials.

The senior officials described the Obama team's phone calls as making clear to the Arab League that bombing Gadhafi's air defenses falls within the Security Council resolution's scope of imposing a no-fly zone and taking "all necessary measures" to stop the dictator from attacking civilians in his own country.

"We don't believe this goes beyond the resolution," said one senior administration official.