NEW YORK, Aug 25 (Reuters) - Oil prices fell about 4% to a one-week low on Tuesday as traders shrugged off the latest U.S. sanctions campaign against Iran, viewing economic pressure as posing less risk to oil supplies than a military escalation.

Brent crude futures were down $3.83, or 4.2%, to $88.34 a barrel by 11:44 a.m. EDT, while U.S. West Texas Intermediate crude futures fell $3.34, or 3.9%, to $81.67.

 Gold prices inched down from a more than three-month high on Tuesday, as investors eager for the interest rate outlook awaited upcoming U.S. inflation data and a speech from Federal Reserve Chair Kevin Warsh this week. 

At 09:12 ET (13:12 GMT), spot gold had dropped 0.4% to $4,632.87 an ounce, while gold futures had fallen 0.2% to $4,686.86 an ounce.

The U.S. dollar struggled to generate sustained momentum on Tuesday, drifting sideways near three-month lows as foreign exchange desks weighed Washington’s expanded sanctions against Tehran against unresolved U.S. fiscal anxieties and a cooling yield advantage. 

The Dollar Spot Index edged up 0.1% to 98.89, following a modest 0.2% tick higher overnight. Despite the slight bounce, the greenback remained anchored within striking distance of its three-month low of 98.5 touched last week, reflecting a reluctant market posture toward aggressive long-dollar exposure.

 Bitcoin steadied above $78,000 after briefly hitting an over three-month high on Tuesday as growing uncertainty over U.S. fiscal health weighed on the dollar and spurred extended flows into cryptocurrencies. 

The world’s largest crypto edged up 0.1% to $78,644.8 by 09:29 ET (13:29 GMT), briefly hitting a three-month high of $81,300.0.