Bush's tough message came in a speech to mark the US independence day in front of 25,000 or so military personnel and families at the Wright-Patterson air base in Ohio.
"The United States will not stand by and wait for another attack or trust in the restraint and good intentions of evil men," Bush said.
"We are on the offensive against terrorists and all who support them. We will not permit any terrorist group or outlaw regime to threaten us with weapons of mass murder. We will act, whenever it is necessary, to protect the lives and the liberty of the American people," he said.
During his speech, Bush did not directly discuss the situation in Iraq where US soldiers have increasingly become targets in resistance operations.
Instead, the US president dwelled upon the war on terrorism.
"Our nation is still at war. The enemies of America plot against us. And many of our fellow citizens are still serving and sacrificing and facing danger in distant places," Bush said.
A USA Today/CNN/Gallup poll this week found the share of Americans who said things were going well for US forces in Iraq had dropped to 56% from 70% a month ago.
Some 50,000 protestors are expected to converge in Philadephia to protest against the US war in Iraq to coincide with the Fourth of July celebrations, organisers said.
But the capital of Pennsylvania state also witnessed the inauguration of its new National Constitution Center, a museum to educate the public about the US Constitution in the city where the Constitutional Convention was held.
During a celebrity-studded ceremony near Liberty Bell, Supreme Court Justice Sandra Day O'Connor accepted the Philadelphia Liberty Medal.
"It is not enough to simply read or even memorise parts of the Constitution," she said. "We should try to understand the ideas that gave it life."
As if responding to her remarks, a group of Muslim Americans later gathered near the Liberty Bell to read the Bill of Rights, pray and express their concerns about civil liberties following the September 11 attacks.
Muslims in the US have complained that they are being discriminated against and are not being given their legal rights as a result of the attacks in New York and Washington.