 Barack Obama has been a member of the church since the early 1990s |
The Illinois senator said the 2001 comments, which have resurfaced on the web, were "completely inexcusable".
Mr Obama said he had not been present during Rev Jeremiah Wright's sermon, at the Trinity United Church of Christ.
The black Chicago pastor brought Mr Obama to Christianity, officiated at his wedding and baptised his daughters.
Mr Obama, a member of the church since the early 1990s, posted a blog on the Huffington Post about his relationship with the pastor, who is now retired.
"I categorically denounce any statement that disparages our great country or serves to divide us from our allies," he wrote.
'God damn America'
Mr Obama, who conducted a number of media interviews on Friday to reject Mr Wright's comments, said he had looked to him for spiritual - not political - guidance.
In a sermon on the Sunday after the attacks of 11 September 2001, Mr Wright told his congregation: "We have supported state terrorism against the Palestinians and black South Africans, and now we are indignant because the stuff we have done overseas is now brought right back to our own front yards.
"America's chickens are coming home to roost."
In a 2003 sermon, Mr Wright said blacks should condemn the US.
"God damn America for treating our citizens as less than human", he said.
Mr Obama said he expects his political opponents will use videos of the sermons to attack him as the campaign goes on.
He is locked in a close race with New York Senator Hillary Clinton for the Democratic nomination, ahead of Pennsylvania's primary vote on 22 April.
