The statement, which appeared on an al-Qaida Web site, said, "All compounds, bases and means of transport, especially Western and American airlines, will be a direct target for our coming operations in the near future."
The statement urged Muslims to stay away from Westerners to avoid becoming victims of the attacks.
"We also warn security forces and guards of Crusader (Western) compounds and American bases and all those who stand with America, its agents ... and the tyrants of the Saudi government, and urge them to repent," the statement added.
Also Monday, one U.S. soldier was killed and two others were wounded when their Humvee hit a bomb in Afghanistan's Uruzgan province, which Taliban guerrillas had planted, according to Uruzgan's Gov. Jan Mohammad Khan.
"All three soldiers were flown to Kandahar airfield hospital where the one soldier died," the military said.
The attack occurred in the Deh Rawud district, an area where U.S.-led forces have been working since last week to help improve security for Afghanistan's upcoming national elections in September.
Since the United States attacked Afghanistan in 2001, 57 U.S. soldiers have died in combat.
Also according to Khan, 40 Taliban soldiers were killed in an operation backed by U.S. aircraft aimed at guerrillas five days ago in the Uruzgan, Zabul and Kandahar provinces.