Ships off Somalia need extra protection because of the upsurge in piracy in the region, a UK maritime union has said.
The ship was on a cruise from Alexandria in Egypt
Andrew Linnington, of the union Numast, called for a naval task force to try to stop attacks, plus danger pay for sailors working in Somali waters.
He made the plea following an attack on a US-owned cruise ship on Saturday.
The Seabourn Spirit successfully beat back gunmen in speedboats who opened fire on it in an apparent pirate attack which terrified passengers.
At least two boats closed in on the Seabourn Spirit, firing automatic weapons and rocket-propelled grenades at the cruise liner.
But the crew took evasive action, repelling the attackers without returning fire.
One crew member was lightly injured in the early-morning incident in waters about 100 miles (160km) off the Somali coast.
Mr Linnington said the region had become so dangerous it should be declared a war zone - a technical term that would grant extra rights to sailors working there.
"It's got to the stage where it's anarchy, and this latest incident shows it's time governments got their acts together," he said.
There have been at least 23 attacks since March against vessels off the southern and eastern coasts of Somalia - not including the one on the Seabourn Spirit, the International Maritime Bureau (IMB) said.
Two weeks before the raid on the cruise ship, the Bureau said the region had become "a pirate's charter".
"Unless the international community takes action against these criminals, vessels passing this coast face considerable danger," IMB director Pottengal Mukundan said.
Pirates seize ships and crews to hold them for ransom, the organisation said.
Saturday's attack was consistent with methods used in earlier raids this year.
The IMB said pirates appeared to have the protection of local warlords in Somalia.
The country has lacked effective central government since 1991.
'First' luxury liner attack
The Bahamian-registered Seabourn Spirit was carrying 302 passengers and crew, most of them are believed to be Americans as well as some Britons and Australians.
"My daughter saw the pirates out our window," passenger Edith Laird from Seattle in the US told the BBC News website in an e-mail from the ship.
"There were at least three RPG that hit the ship, one in a stateroom four doors down from our cabin," she said.
A scheduled stop in Mombasa, in neighbouring Kenya, has been cancelled and the cruise, which began in the Egyptian port of Alexandria is now due to end in the Seychelles on Monday.
The attack appears to be the first on a luxury cruise liner in the area.