Briefing representatives of all 202 nations taking part in the August 13-29 Olympics, Games chief Gianna Angelopoulos said every measure was being taken to ensure the safety of the world's biggest sporting event.
She said unwarranted criticism of the security plans could play into the hands of militant groups seeking to undermine the Games.
"I am concerned that we send a consistent message to those who wish us ill," an angry Angelopoulos said.
"Telling them that there are holes in Athens security procedures and that our preparations can be circumvented when all our preparations are designed to achieve the opposite is bad security strategy."
Greece, hosting the first summer Games after the September 11, 2001 attacks on U.S. cities, is implementing the biggest ever Olympics security plan, worth 1.0 billion euros.
International Olympic Committee president Jacques Rogge backed organisers, saying the Games would be successful.
"A few days before the Olympic Games, which I have no doubt will be successful, let me thank ATHOC (the Games organising committee) for a formidable partnership," he told an Olympics youth meeting in Athens.
Rogge is expected to meet Greek Prime Minister Costas Karamanlis to discuss preparations.
Australia angered Games organisers and the IOC two weeks ago by issuing a warning to travellers to be cautious if visiting Greece after three bombs exploded in Athens three weeks ago.
The host of the 2000 Sydney Olympics is a member of the seven-nation
"Australia chose the middle of a successful (IOC) meeting to release a warning regarding travel to Greece," Angelopoulos said. "Suggestions that we don't take our security preparations seriously is wrong."
Public Order Minister George Voulgarakis, who heads Olympic security planning, told the security meeting the Games would be safe.
"I want to make it clear that we will not put the people and the event in danger. We can guarantee a safe Olympic Games," Voulgarakis said.
Angelopoulos said the recent barrage of international media reports and Australia's travel advisory questioning security arrangements could put athletes under stress.
"We want athletes to have only one concern this summer as the world looks on: delivering an Olympian performance," she said. "Unnecessarily raising their anxiety levels with uninformed comments can only distract young men and women."
With 45,000 armed guards, NATO air and sea patrols, and a network of thousands of cameras for crowd and traffic control, the security measures far exceed those for the Sydney Games.
Athens Games organisers have staged a series of large-scale exercises on nuclear, biological and chemical threats, hostage situations, hijackings and other threats.
But a series of minor bomb attacks over the past weeks, which the Greek government has dismissed as "isolated domestic events", have again raised security concerns.