During safety tests, the crew could not hit the 30-minute limit for getting passengers off the ship in the event of an emergency. Emergency power sources failed and the lifts that lower lifeboats into the water failed to work properly, said Janet Espino Young, the Coast Guard's chief of inspections.
The high-speed cruise ship is already four days behind schedule, The Miami Herald reported Tuesday.
The ship was expected to set sail last Friday to the Resorts World Bimini casino, the newspaper said.
The crew was able to demonstrate Saturday it could evacuate passengers in the required time, but other issues are keeping the ship in its berth for now, the Coast Guard said.
The ship was built in 2001 and has been in used around the Greek isles.
It was then certified as safe by authorities in Panama, which the company presumed was good enough to satisfy U.S. safety regulators, the Herald said.
That turned out not to be the case. The ship has been in U.S. waters for two weeks. But U.S. regulations are much more stringent than Panama's, Espino-Young said.
"Even if it is a 2- to 3-hour trip to Bimini, we need to make sure passengers are not put in high-stress, threatening situations," she said.
The company Friday went ahead with a christening event that included 600 guests.
"We will provide information about the SuperFast's inaugural sailing as soon as it becomes available," President Dana Leibovitz of Resorts World Miami said in a statement.