American diplomats have called on Cuba to release a US citizen held since December without charge.
The release of Alan Gross, 60, was discussed during talks about migration in Havana, the US said.
Cuba's president has accused him of spying, but his family say he was distributing communication equipment to Jewish groups.
The issue has overshadowed the resumption of high-level talks between the Cold War adversaries.
Top diplomats from both countries held talks for about five hours in Havana, focusing on migration issues.
Afterwards the Cuban government said the meeting had taken place "in an atmosphere of respect", but made no mention of Mr Gross's case.
The US says he went to Cuba on a programme funded by the US Agency for International Development, and he had visited the country before on the same programme.
Cuban President Raul Castro has said Mr Gross used "sophisticated" communications equipment to help opposition groups in their role as "mercenaries" for the US, AFP news agency reported.
Apart from the issue of the detention, the US State Department said that "engaging in these talks underscores our interest in pursuing constructive discussions with the government of Cuba to advance US interests on issues of mutual concern".
The US delegation was led by Craig Kelly, Deputy Assistant Secretary of State for Western Hemisphere Affairs - the most senior US official to visit Cuba in many years.
The two sides used to hold regular, twice-yearly immigration talks, aimed at avoiding the mass exodus of Cubans.
But the Bush administration froze all contacts with Cuba.
Relations have eased under President Barack Obama with the resumption of direct negotiations on areas of mutual interest.
He has also lifted all restrictions on Cuban Americans visiting and sending money to relatives on the island.