The bus was carrying 31 passengers before it lost control and rolled – Brazilian and Swedish citizens were also among the group, according to authorities.
The incident happened during a visit to ancient ruins on Mexico’s Yucatan Peninsula in Quintana Roo.
Spokeswoman Cynthia Martinez stated that 27 of the passengers were travelling on Royal Caribbean cruise ships.
She said: “Our hearts go out to all those involved in the bus accident.
“We are doing all we can to care for our guests, including assisting with medical care and transportation.”
The ancient Mayan suit in the zone of Chacchoben was the coach’s destination before it steered off the Chetumal-Mahahual highway on Tuesday.
Bus company Costa Maya revealed that passengers were taken to hospitals following the incident – five have been discharged and those injured are in a stable condition.
A child was among the 12 dead.
Quintana Roo’s government are investigating the cause of the incident.
The US embassy in Mexico is also working with authorities to establish further details on those involved.
Last year 11 were killed when a bus flipped in the same region while travelling to popular tourist spot Cancun.