In the Internet video, Cain's sings over images of the terrorist-hijacked jetliners slamming into the World Trade Center twin towers and other jarring images of the attacks, along with photos of rescue operations and people mourning afterward.
In a Twitter post Friday on his presidential campaign Web site, Cain said the attacks showed "the worst of our enemies, but ... the best of us."
"In a time of utter chaos and despair, Americans of all walks of life united under our flag for the cause of caring for one another and our country," he wrote. "Although we shall never forget the loss of precious life on that Tuesday morning, terrorists did not and will never win, for the spirit of America- the triumphant spirit that has sustained us for more than two centuries- was reaffirmed, even in our darkest hour."
He went on to say the United States remains "the envy of the world."
"That's why, ten years later, we must answer the high moral call for defending this great nation for Her preservation for generations to come," he said.
"In honor of the fallen and those who continue to sacrifice for our sake, may we be ever mindful of the goodness of our people, our resiliency through trials and God's continued grace upon this land."