The match official initially opted to delay the start as groundstaff worked feverishly to clear some of the surface water from the pitch.
But the rain which had been falling for much of the day became heavier, producing several areas of standing water, and leaving Naylor no option but to call the game off at 3.10pm.
Watford boss Zola said: "Looking at the pitch, it was impossible to argue with the referee's decision.
"The players would have found it impossible to perform with so much water on the surface so I'm pleased the right decision was made."
City manager McInnes added: "I did ask if the ref would consider on until 4pm to see if the rain stopped.
"But by the time I went out with him for another inspection it was clear conditions were not improving and he probably did the right thing."
McInnes said groundstafff had been taken by surprise by the amount of rain that fell.
"The weather forecasts had been checked an no one foresaw a problem," he said. "The first I knew the game was on doubt was at 2.45pm when I was summoned to the referee's room."
- Sports & Recreation
- Nature & Environment