Merchant vessels have been among targets for Somali pirates
The United Nations Security Council has unanimously approved a US resolution allowing countries to pursue Somali pirates on land as well as at sea.
It is an extension of the powers countries already have to enter Somali waters to chase pirates.
China said it was seriously considering sending naval ships to the region, but will first need permission from the transitional Somali government.
The move came as several vessels were seized by Somali pirates off Yemen.
On Wednesday morning pirates were reportedly foiled after attempting to attack a Chinese-owned ship in the Gulf of Aden - a day after three other vessels were seized.
The Chinese crew held off the pirates long enough for back-up to arrive, AFP news agency reported.
"Military helicopters came and they managed to chase the pirates away," Noel Choong, of the International Maritime Bureau, told AFP.
The BBC's Peter Greste in Nairobi says the latest attacks appear to be a calculated jab at UN attempts to clamp down on piracy.
He says they bring to 42 the number of successful hijackings in the area this year.
Fourteen foreign ships and their crew of over 200 are still being held, our correspondent adds.
A surge in pirate attacks has proved costly to international shipping
Tuesday's UN resolution was the fourth approved by the Security Council since June to combat piracy off Somalia's coast.
It gives authority for one year for countries to use "all necessary measures" by land or air to stop anyone using Somali territory to plan, help or carry out acts of piracy and armed robbery at sea.
The US-drafted resolution was co-sponsored by Belgium, France, Greece, Liberia and South Korea.
Indonesia, which also suffers from piracy, was among critics of the plan as it feared the precedent it could set for chasing pirates on land. But in the end it voted in favour.
One of the vessels seized on Tuesday was a Malaysian tugboat which had been heading home through the Gulf of Aden from the Middle East.
According to the International Maritime Bureau, pirates boarded the vessel armed with rocket propelled grenades and automatic weapons.
A Turkish cargo ship, MV Bosphorus Prodigy, owned by Isko Marine Company, was also captured, a US Fifth Fleet spokesman said.
The container ship is 330ft (100m) long and was carrying the flag of Antigua-Barbuda.
And a private yacht was seized.