"Yesterday, London and Madrid. Tomorrow, Los Angeles and Melbourne, Allah willing," the man said in the 11-minute tape. "We are Muslims. We love peace, but peace on our terms, peace as laid down by Islam, not the so-called peace of occupiers and dictators."
U.S. intelligence officials say they believe the man speaking is Adam Gadahn of Orange County, Calif. His family says he converted to Islam at an Orange County mosque, where he came under the influence of militants who took him to Pakistan, and he has since emerged as an al-Qaida propaganda tool.
However, Los Angeles Mayor Antonio Villaraigosa said Sunday city residents should go about their normal business, USA Today reported.
"Bombastic pronouncements are expected on the anniversary of terrorist incidents like Sept. 11, (2001)," Villaraigosa said in a statement. "The best thing any Angeleno can do is go about his or her daily life as you normally would," they advised.
Australian officials said they would not comment until they had analyzed the tape.
Scarlett Johansson steps out with fiance after pregnancy reveal
Susan Sarandon 'very excited' about daughter's pregnancy