Marella Cruises has cancelled all sailings from 14 to 28 March.
The Tui-owned line said impacted customers would be “proactively notified and automatically issued a full refund”.
TTG is awaiting comment from Marella on how the announcement may impact the launch of its new river cruise fleet, set to debut in Amsterdam on 28 March.
A spokesperson added: “The cruise line understands that this may be disappointing for customers but felt that given the constantly changing situation cruises operating during the next two weeks would fall short of the experience it wants to give its customers.
“Marella Cruises would like to thank its customers for their understanding during this unprecedented time.”