The Dutchman, who has World Cup gold on the merit list and came second in the Tokyo Olympics some time ago, broke a bone in his right wrist in the accident and underwent surgery on Friday.
"It's a big disappointment that I'm back in good shape again.
I felt very strong during the training and felt that I had a very good month ahead of me ", says Dumoulin in a statement from the stable Jumbo-Visma.
Last year, Dumoulin took a five-month break due to mental illness.
The World Cycling Championships take place in Belgium between 19 and 26 September.