Bad weather conditions have prevented Icelandic whalers from carrying out their first hunt for 15 years.
High winds and choppy seas halted vessels which were set to leave on a six-week mission to kill 38 minke whales.
Iceland's government said it was embarking on a scientific whaling programme, and authorities had been due to issue permits on Friday.
They say the mammals have become so abundant since a worldwide moratorium on commercial whaling that they are threatening stocks of fish, including cod.
But the decision was attacked by the UK and US Governments, as well as animal welfare groups.
The International Fund for Animal Welfare (Ifaw) says there is no scientific basis for the operation, and that Iceland cannot use science to camouflage its desire to resume commercial whaling.
In Britain, the Royal Society for the Prevention of Cruelty to Animals is stopping short of calling for a boycott of Icelandic products, but it is asking consumers to think twice before buying fish from the island.
Iceland's own tourism industry has joined in the criticism, fearing that the decision could damage the country's image, and threaten the increasingly popular whale-watching business.
"Whaling is part of Iceland's past, and must remain so," Greenpeace Executive Director Gerd Leipold said in a statement.
"While we don't expect to change everyone's minds, Greenpeace hopes that we are able to give many Icelanders the confidence to say no to whaling - forever."
Three ships were due to set sail from undisclosed locations over the coming days to avoid possible protests.
Iceland has not hunted whales since 1989.
ICELAND AND THE WHALE
1986: International moratorium on commercial whaling
1989: Iceland halts whaling
1992: Iceland quits IWC
2002: Rejoins IWC
2003: Resumes whaling
It left the International Whaling Commission, the body that regulates world whaling, in 1992.
But it rejoined in 2002 on condition that it was allowed to register its objection to the moratorium on commercial whaling that has been in place since 1986.
Earlier this year, it said it wanted to hunt 100 minke, 100 sei and 50 fin whales.
The original proposal was discussed at the recent Berlin meeting of the IWC - but not voted on.
Icelandic officials say that by restricting its operation to 38 minke, the country is showing it is ready to compromise with its critics.
Stocks of minke are internationally acknowledged to be abundant, they say.
The environmental organisation Greenpeace has recalled its flagship Rainbow Warrior for a mission to Iceland.
The ship, which campaigned against Icelandic whaling on its maiden voyage in 1978, is due to arrive in two weeks.