It was the first time Castro had attended a summit attended by all Latin American leaders in eight years.
The summit is the largest in the Western hemisphere to exclude US representation and has been hailed as a sign that Latin America is demanding a new independence from Washington.
"The presence of Cuba is a very strong signal that America is no longer the boss in Latin America," Hugo Chavez, the Venezuelan president, said as he arrived.
On Monday, Castro told Al Jazeera that the US must make concessions first if the two countries are ever to restore diplomatic ties severed for more than 40 years.
|Castro, left, held talks with Hugo Chavez before arriving in Brazil [AFP]
Reports say Luiz Inacio Lula da Silva, the Brazilian president, could mediate between Washington and Havana.
Castro, said the "era of unilateral concessions was over", and insisted that Cuba had only ever defended itself against the US.
"We have never hurt the United States, we have only defended ourselves. We are the ones who have been hurt so we are not the ones who have to make a gesture. Let them do it," he said on Monday.
The Cuban leader said he was in "no hurry" to mend diplomatic relations with the US, which were severed in 1961, following the overthrow of the US-backed government by Fidel Castro's revolutionary movement.
The US imposed a series of economic sanctions in 1962 that has been reinforced by successive presidents.
"More than 70 per cent of Cubans were born under the blockade which has been in place for almost 50 years," Castro said.
"I'm 77-years-old but I feel good and young. In other words if this doesn't get resolved now, we'll wait another 50 years."
Chavez and other leaders also said the election of Barack Obama as US president has created a key opportunity for South American countries to speak with their own voice and to demand respect in a new dialogue with the United States.
Castro also said the Cuban government was ready to hold talks with Obama, the US president-elect, after he takes office on January 20.
"We are impulsive like the Brazilians but over the years we have also learned to be patient. So we are not desperate. In other words if Mr Obama wants to talk, we will talk and if he doesn't, we don't."
Obama said during his successful presidential campaign that he was prepared to consider holding talks with nations perceived to be hostile to the US, such as Cuba.