One boat scraped with another while trying to dock in the Mexican resort of Cozumel.
It damaged at least one of the boats and resulted in minor injuries to six passengers.
Carnival Cruise Line said the Carnival Glory was manoeuvring in the port when it "made contact" with the Carnival Legend.
Videos showed the noisy, slow-moving accident, which left part of the Glory visibly mangled at the stern.
The cruise line said it was assessing the damage.
However, it said there were "no issues that impact the seaworthiness of either ship".
It said six guests came to the Glory's medical centre for evaluation for minor injuries.
According to Carnival's website, the Glory sails from New Orleans on cruises to the Caribbean and the Panama Canal.
It is 952ft long with a guest capacity of 2,980.
The Legend operates from multiple ports in the US and Europe to a variety of destinations.
It is 963ft long with a capacity of 2,124.
