Carnival Vista will sail from Galveston on 3 July, with Carnival Breeze returning to the port on 15 July.
Cruises are available for guests who have received their final dose of an approved vaccine at least 14 days before departure and who have proof of vaccination.
Carnival president Christine Duffy said regulations made it impractical to carry unvaccinated guests.
“As a result, our alternative is to operate our ships from the US during the month of July with vaccinated guests.”
Also scheduled for a July restart is Carnival Horizon from PortMiami.