The automaker declined to give a reason for the delay or be more specific about the timing.
A spokesman said it would reduce initial production of the model, although output would eventually pick up according to demand.
Previously, Toyota had said that it would begin sales of the plug-in version in Japan in autumn, and that the model would become available in North America and Europe around late autumn.
Sales of the standard version of the fourth-generation Prius, the forefather of the "eco car", have been sluggish in the United States since it went on sale around February, as low petrol prices have ramped up demand for gas-guzzling SUVs and pick-up trucks.
Meanwhile, it has been the best-selling model in Japan since the start of the year.
