Fighting between the Israeli military and Palestinian militants in Gaza has added to the risk of instability in the oil-rich Middle East just as tensions have intensified between the West and Russia, a major oil and gas producer, over the Ukraine crisis.
European leaders are considering tougher sanctions against Russia for its backing of separatists accused of shooting down the Malaysia Airways passenger plane in Ukraine last week. The European Union's foreign ministers were meeting to discuss their next steps.
Investors will also be monitoring fresh information on U.S. stockpiles of crude and refined products.
Data for the week ending July 18 is expected to show a draw of 2.6 million barrels in crude oil stocks and a build of 1.2 million barrels in gasoline stocks, according to a survey of analysts by Platts, the energy information arm of McGraw-Hill Financial.
In other Nymex trading:
Wholesale gasoline fell 1 cent to $2.88 a gallon.
Heating oil was flat at $2.85 a gallon.
Natural gas dropped 1 cent to $3.77 per 1,000 cubic feet.