Cuba's Ricardo Cabrisas and his Spanish host Luis de Guindos laid the "groundwork for an agreement on putting in place new conditions...concerning short-term (Cuban) debt" held by Spain, the Spanish government said in a statement.
Madrid released no further details on any modifications, saying it is awaiting the ratification of the agreement between the two countries.
This meeting comes less than a month after US President Barack Obama and his Cuban counterpart Raul Castro formally reestablished diplomatic relations between the two nations, which had been cut off since 1961.
Spain's conservative government hopes to benefit from this thaw and has undertaken moves to restore relations with its former colony. Earlier this month a delegation of Spanish business and political leaders visited Cuba.
"Cuba represents a new opportunity for Spanish investments," said the government statement.
"Cuban and Spanish authorities are actively working to expand their economic, business and financial relations," it added.
Cabrisas made his stop in Madrid while en route to Cuba after a visit to Angola, the Cuban embassy said. The last visit of such a high-ranking official from the island regime dates to 2005.
Spain has been criticised for its delay in resuming full relations with Cuba.
The Caribbean nation and the European Union have since 2014 been negotiating a normalisation of their relations, talks Madrid hopes to energise after falling behind the United States' rapprochement.