The London-based Union of Greek Shipowners and the Greek Shipping Cooperation Committee issued the joint warning after holding talks with Greek Minister of Mercantile Shipping George Voulgarakis in London.
"Sea transport is the best way of preserving the environment," the statement said, underlining that it was the least polluting form of transportation.
It said moves to include shipping companies -- which have so far escaped emission-cutting regulations -- would "lead to a fall in maritime trade ... and raise the price of goods and services."
About 90 percent of of world trade by volume moves on sea, according to estimates.
A soon-to-be published UN study reproduced in the British press says the annual carbon dioxide emissions from shipping total 1.12 billion tonnes per year, or 4.5 percent of the world's total.