The Iraq war helped bring a democratic "wave of change" to the Middle East, the UK foreign secretary has said.
Mr Straw addressed the left-wing think tank the Fabian Society
Labour supporters, many of whom opposed the war, should not dismiss US policy simply because it is headed by a right-wing president, Jack Straw says.
He argued the war was not the only factor, but added: "We don't think this is nothing at all to do with Iraq."
He said changes in Egypt, Saudi Arabia and Lebanon are also due to Al-Jazeera TV and the Palestinian leadership.
Mr Straw is the first senior minister to address the divisive issue of Iraq since unofficial campaigning began for the general election, predicted to be called for 5 May.
There are some fears within the Labour Party that anger over military action might lead to a low turnout among some traditional supporters.
Mr Straw said: "It will be for historians to judge ... just how much the end of the Saddam regime in Iraq, and the free elections there in January, have contributed to what is now happening.
"But I do not buy the claim that his has nothing to do with Iraq, or America, or the west."
The Bush administration argues that a successful democracy in the Middle East could encourage reform throughout the Arab world.
Mr Straw told the Labour-affiliated Fabian Society: "Faced with an American government of the Right promoting a vision of how to change the world for the better, many on the Left have become the staunchest advocates of the status quo.
"For them, President Bush's commitment to promoting freedom and democracy is simplistic; misguided; or as simply a veil for more sinister motives.
"But whatever the differences of opinion over Iraq, it would be highly dangerous for the Left to settle into a comfort zone as the opponent and critic of American power and American objectives in the world."
'Comfort zone' danger
He added: "Democracy is not just a Western value, nor is it true that it is the Islamic religion which blocks democracy in the Middle East."
Prime Minister Tony Blair has recently hailed the "ripple of change" in the Middle East, following a London conference on Palestinian reform attended by the new Palestinian leader Mahmoud Abbas.
Other developments include elections in Iraq and Afghanistan, protests against Syrian troops in Lebanon, municipal elections in Saudi Arabia - although not for women - and possible changes to the constitution in Egypt to allow multiple candidates in presidential elections.
Mr Straw stressed that humility was a key element in supporting the process of change in the Middle East, adding: "Change is rarely quick, or simple. We know well from our own history that the constitutional arrangements which we have today in the United Kingdom are the result of a long and often passionate struggle."