3,000 protesters carrying Cuban flags, mostly students and trade union members, set fire to a US flag in Cartagena on Saturday.
They also chanted slogans against the presence of US President Barack Obama in Colombia.
On Saturday, President Obama tried to convince skeptical Latin Americans that Washington had not turned its back on them -- but a prostitution scandal involving US security personnel marred the charm offensive.
The fate of the summit’s final declaration remains uncertain. Venezuela, Argentina, and Uruguay have said they will not sign it unless the US and Canada drop their veto on future Cuban participation.
Cuba, which is not a member of the Organization of American States, was not invited to join the summit. But there was a last-minute push by Ecuadorian President Rafael Correa to get Cuban leader Raul Castro a seat at the table.
Correa boycotted the summit because of Cuba's exclusion.
Within hours of the arrival of US President Barack Obama, a series of explosions occurred, marring the opening of the event. However, no injuries or damage were reported.