"Tourists and Rome residents were expecting navigation for the year to resume at Easter. But we didn't open out of respect for them," said Mauro Pica Villa from "Rome Boats", the company in charge of all cruises on the river.
"We're ashamed of the Tiber's state of abandonment," he told AFP on Thursday.
The river's tall stone embankments have become grey with pollution, the river banks are strewn with rubbish and homeless people live under the bridges.
"The last time the river was cleaned up was in 2008! Everyone can see it since trees along the Tiber are covered in plastic bags and other rubbish every time the river overflows," which happens several times in a year, he said.
Making navigation even more difficult, Pica Villa said, is a 1906 law still in place that classifies the waters of the tiber as "maritime" and not "communal" property meaning Rome city hall is not responsible for the upkeep.
Former Rome mayor Walter Veltroni launched the river cruise services in 2003 and they were initially very successful, selling 40,000 tickets a year.
Pica Villa said it was a shame to be suspending the services, which included tours about the history of Rome's bridges and romantic dinner cruises.
The Tiber is Italy's third longest river and runs 400 kilometres (250 miles) from the hills of Tuscany to the port of Ostia on the Mediterranean.