The U.S. imposed an embargo on Cuba in 1962, three years after the Cuban Revolution that saw the downfall of Washington-backed dictator General Fulgencio Batista.
The declaration followed a regional summit on integration and development in the Brazilian resort of Bahia.
Obama has stated that he will maintain the embargo in a bid to bring about democracy on the island. In May of this year, former Cuban president Fidel Castro commented that then-presidential hopeful Obama's policy could "be translated as a formula for hunger for the country."
In October, the UN General Assembly overwhelmingly passed a resolution "on the need to end the economic, commercial and financial embargo imposed by the United States against Cuba."
Cuban President Raul Castro described as a "transcendental moment" Cuba's formal acceptance on Tuesday into the Rio Group of Latin American nations, an international organization of 20 Latin American and Caribbean states.
The two-day summit, which finished on Wednesday, involved heads of state and governments from 33 regional countries. Neither the United States nor any European nation was invited to attend the forum, widely-seen as an expression of regional independence.
In the declaration, summit participants confirmed their intention to protect the sovereign rights of every nation in the region to build its own political system, free from threats and aggression.
The summit also focused on the ongoing global financial crisis. Regional leaders expressed deep concern over the crisis and put the blame for it on developed nations, saying they "caused the crisis and... should, therefore, assume the costs for its solution."
The leaders also urged action as soon as possible toward energy integration between Latin American and Caribbean countries amid the widening gap between supply and demand on the global energy market.
A number of countries in the region have been expanding military, economic and diplomatic contacts with Russia, as well as China and Iran, in a bid to counterbalance U.S. global and regional dominance.
Russian warships will visit the port of Bluefields in Nicaragua on December 12-15 following a joint naval exercise with Venezuela and a visit to Panama.