Raul Castro at the Latin American and Caribbean summit in Costa Rica on Wednesday.
Mr Castro issued his demands a week after the highest-ranking US delegation to Havana in 35 years and Cuban officials held landmark talks aimed at reopening embassies and renewing ties that broke off in 1961.
The Cuban leader, brother of former president Fidel Castro, also warned Washington to cease interference in Cuba's internal affairs.
"If these problems are not resolved, this diplomatic rapprochement between Cuba and the United States would be meaningless," he said.
Cuba has long blamed the embargo for the communist island's economic woes, with billboards in the country equating the decades-old economic sanctions to a "genocide".
Speaking at a summit of the Community of Latin American and Caribbean States in Costa Rica, Mr Castro said that the road to ending the embargo would be "long and hard".
US President Barack Obama called on Congress last week to put an end to the embargo, which was imposed in 1962 and has been a major source of tension between the Cold War-era rivals since then.
Earlier this month, Mr Obama used his executive powers to ease travel and trade restrictions with Havana, putting a dent on the embargo.
But Mr Castro said that the US leader should do more.
"He could use with resolve his broad executive powers to substantially change the scope of the blockade, even without the Congress decision," he said.
The 33-nation summit is expected to issue a declaration condemning the embargo. The group, which does not include Washington, was created by the late Venezuelan socialist leader Hugo Chavez.
"Enough with the criminal blockade of Cuba," Ecuador's leftist President Rafael Correa told the summit. Nicaraguan counterpart Daniel Ortega said the embargo "will have to disappear."
Mr Castro and Mr Obama simultaneously announced on December 17 their intention to end half a century of animosity and normalise ties.
Some US politicians have voiced concern about the rapprochement, especially those of Cuban-American origin, who say Mr Obama conceded too much to Mr Castro without securing guarantees of political change on the island.
The United States has invited Cuba to hold another round of talks in the coming weeks in Washington.
In his speech in Belen, Costa Rica, Castro said that Havana also wants to be removed from a US blacklist of state sponsors of terrorism, which has blocked Cuba's access to financial institutions.
In addition, he demanded the return of Guantanamo Bay, where the US navy has a base being used to jail terrorism suspects.
Agence France-Presse, Reuters