"The vessel is stable. Port officers are looking at how to refloat it," an official in the local administration told AFP, without giving his name.
A spokeswoman for the P&O shipping company said the ferry, The Pride of Kent, ran aground after it hit a gangway while making to leave for Dover, its destination in Britain.
There were 316 people on board -- 208 of them passengers, government officials said.
More than nine million passengers used Calais to cross the channel in 2016, according to official numbers.