"Pre-operational screening may include unusual activities or behavior in and around gas stations and targeting of underground fuel-storage locations," FBI said in a statement.
The bureau said it has no information indicating specific targeting of the U.S. fuel infrastructure, but noted such targeting would be consistent with Al-Qaeda's stated objective to disrupt and undermine vital economic interests.
FBI said hijacking or theft of fuel tankers are listed as possible acts being planned. There was an attempt Monday outside Indianapolis, the bureau stated.
According to FBI, two men allegedly tried to force the truck, which was carrying 10,000 gallons of gasoline, to stop at gunpoint.
Officials said the driver of the tanker truck contacted his dispatcher at McDaniel Transport, who advised him not to stop in a remote area, but to instead drive to a more populated area.
"Given all of the threats reporting that Al-Qaeda operatives in the U.S. may attempt to attack either gas stations, fuel-storage depots or the tanker trucks themselves, we were very concerned that that might be an issue," FBI Special Agent in Charge Tom Fuentes said.