In Thursday's trading, the dollar index closed nearly flat. Although Trump stated that the United States would not attack Iran before the November 3 midterm elections, renewed market concerns over escalating tensions in the Middle East pushed oil prices higher.

The dollar spot index fluctuated between gains and losses during the session before ending essentially unchanged.

Brent crude briefly climbed above $105 per barrel, then gave back some of its gains. Meanwhile, a hurricane in the Atlantic disrupted some U.S. crude production.

Following strong demand at the 30-year Treasury auction, yields fell 7 basis points to 5.6%.

EUR/USD rose 0.1% to 1.1211. GBP/USD rose 0.1% to 1.3227. Bank of England rate-setter Megan Greene said that in the face of a global energy shock, judgments must now be made about the risk of entrenched inflation. USD/JPY fell 0.1% to 157.88.