But Yiannos Papantoniou said he had no information Greece was being specifically targeted by terrorists.
Greece has budgeted a record of more than $750 million toward protecting the Aug. 13-29 Olympics and plans to deploy more than 40,000 police, military and coast guard to safeguard venues across the country.
The United States, Britain, Israel, France, Germany, Australia and Spain are part of an advisory group helping with Olympic security.
But bombings in Turkey the past 10 days that killed 57 people have raised concerns that international terror groups could pick a wider range of targets than previously feared. The Turkey bombings targeted synagogues, the British consulate and the Turkish headquarters of London-based HSBC bank.
Investigators are studying possible international Islamic militant links to the attacks, which occurred within a week. Three groups with purported al Qaeda links have claimed responsibility for the Nov. 20 bombings of the consulate and bank.
"There is a high degree of readiness for security, especially following the recent events," Papantoniou said while visiting a central Greece army base. "I want to add that there is no special indication that Greece is a specific target."
Greece was working closely with foreign military forces to have "a flow of information and protection system" in place that will help shield the Olympics.
Britain's top counterterrorism official, Metropolitan Police Assistant Commissioner for Special Operations David Veness, will travel to Athens this week for an advisory group meeting to review security plans.
"We have to take into account that international terrorism is unpredictable. No country can theoretically be ruled out," Papantoniou said. "So we are obligated to take all eventualities into account and to prepare for anything."