SYDNEY, Australia — The Australian government said on Wednesday that it would not grant a visa to Chelsea Manning, a former American soldier sentenced to prison for sharing classified government documents, because she failed a character test required for entry.

Ms. Manning was scheduled to conduct a speaking tour of Australia through September, beginning with an appearance this Sunday at the Sydney Opera House with the American journalists Ronan Farrow, Ta-Nehisi Coates and Maureen Dowd.

On Wednesday, Ms. Manning said she would “work it out,” reported Guardian Australia, and the group organizing the event said it would push for her to be allowed into the country.

“We are very disappointed to learn that the Department of Home Affairs has taken this approach and will be vigorously advocating for her ability to enter Australia,” Think Inc., the event’s organizer, said in a statement on Thursday.