With reports of slower global demand and increased production from some oil-producing states, the oil market could withstand the trauma of imposing sanctions on Iran, a move agreed to by many countries to force Iran to drop an alleged nuclear weapons program.
The White House said the oil market was "relaxed."
West Texas Intermediate crude oil for July delivery in New York dropped $2.63 Monday to $81.47 per barrel.
Natural gas dropped 9.2 cents to hit $2.207 per million British thermal units.
Home heating oil shed 6.17 cents to $2.6104 per gallon.
Gasoline moved 5.52 cents lower to reach $2.63 a gallon.
At the pump, the national average price of unleaded gasoline dropped to $3.54 per gallon from Sunday's $3.542, AAA said.