Spain's decision tightens a global financial chokehold on Qadhafi's regime, its assets already blocked in the United States, Canada, Switzerland, Britain, Austria and Germany.
"We will proceed with the embargo or freezing of Khadafi's assets in Spain," a government spokesman said.
Spain's Foreign Minister Trinidad Jimenez announced the decision to journalists as she accompanied Prime Minister Jose Luis Rodriguez Zapatero on a flight to Tunisia, said the spokesman, who was present.
Zapatero will be the first Western leader to visit Tunisia since the ouster of president Zine El Abidine Ben Ali, who fled to Saudi Arabia January 14 in the face of a popular uprising against his 23-year rule.
Uprisings against authoritarian Arab regimes are now spreading across the Middle East and North Africa.
Forces loyal to Libya's Qadhafi armed with warplanes, tanks and heavy artillery are attacking key towns lost to rebels. Major powers disagree over whether to impose a no-fly zone over Libya.
The Libyan regime's assets in Spain include a 7,065-hectare (17,450-acre) property on the Costa Sol in Andalucia, acquired in 1995 by the Libyan Arab Foreign Bank, owned in turn by Libya's central bank.
The purchase of the property known as La Resinera reportedly made the Libyan regime one of the main land-owners on the Costa del Sol.
Libyan Arab Foreign Bank had proposed in December a plan to build an 18-hole golf course and about 2,000 homes on the land, a regional government spokesman for Andalucia said.
A similar project was planned in 2007 but did not win approval from the Andalucian authorities.
Qadhafi made an official visit to Spain at the end of 2007 when he travelled to Malaga, capital of the Costa del Sol and a haven for tourists and the mega-rich.
Former Spanish premier Jose Maria Aznar was the first Western leader to visit Tripoli after the lifting of UN anti-terrorism sanctions in September 2003.
Spain has tightened its links with Libya since then, notably in energy and construction industries.