Every year thousands of Cubans leave the country illegally aboard fragile boats to try to reach Florida, which is 145 kilometres (90 miles) away.
The provisional agreement was reached yesterday and must now be approved by the governments of each country.
Havana and Washington have not had diplomatic relations since 1961, two years after Fidel Castro came to power in the Cuban revolution.
Under current policy, US-bound Cubans caught on the high seas are repatriated. But if they make it to US shores they are let in, allowed to stay and in a year or so acquire residence papers.