
West Texas Intermediate prices dropped after the United States paused military action against Iran.
The planned bombing campaign targeted energy infrastructure following escalating strikes across the Middle East since April.
"We will neither be caught off guard nor remain passive," said Iran's acting Defence Minister Majid Ibn al-Reza.
The United States government previously blockaded ports and warned citizens to prepare for potential regional escalation.
Washington and Tehran have engaged in retaliatory strikes since a temporary ceasefire fell apart in June.
Polling indicates that 60% of Americans disapprove of the conflict ahead of midterm elections.
"I'm losing faith in them because they do lie and do, they do misrepresent," President Donald Trump says during the meeting at the Camp David presidential retreat in Maryland.