The boat belonging to state-run Inland Water Transport was going from Phulbari to Dhubri town when it hit the rock at around 9.45 AM, police said.
The engine of the vessel stopped under the impact of the collision, leaving the ferry stranded in midstream.
The boat was then pulled to the bank of the river by local people and the passengers were evacuated, the police said.
They were taken to their respective destinations by other ferry boats passing through the area, the police added.
The local people alleged that the ferry boat was old and needed repair.