The divers were assisted by the U.S. Coast Guard until the operation was shut down, Detroit police spokeswoman Eren Stephens said.
No new recovery date was announced.
Once it's recovered, the Detroit Historical Society hopes to restore and preserve the cannon, which is more than 6 feet long and likely weighs about 1,200 pounds.
Three other cannons were recovered in the 1980s and a fourth was recovered by the department's dive team in 1994. Those are believed to be British and French. Detroit Historical Society Curator Joel Stone said the latest find will be studied to try to determine its age and where it came from.
"This is all kind of a detective thing," Stone said. "You get one piece of the puzzle, and then you get another piece of the puzzle."
The cannon could be one of several believed to have fallen into the river in 1796 when they were being transported by the British, Detroit police said. Cannons that have been found in the area, however, also may have gone down anytime up to the War of 1812, Stone said.
Sgt. Dean Rademaker, who took part in the dive when the last cannon was found in 1994, spotted what turned out to be the latest one in July. Department divers previously had been to that area of the river hundreds of times without finding it, Rademaker said.
"I thought to myself, 'You gotta be kidding me,'" he said of the discovery.
Divers more typically find cars and guns. In 2009 during a training session, they turned up a 6-foot, 300-pound bronze statue that had been missing for more than eight years from the Grosse Pointe War Memorial. The statue was returned to its suburban Detroit home.