As oil markets remain jittery, the cargo seizure is the latest escalation between Washington and Tehran after years of sanctions pressure by the US over Iran’s nuclear program.
Heavy clashes, shootings, rocket strikes and a car-ramming attack have marred a period when the Muslim holy month of Ramadan coincides with the Jewish Passover and Christian Easter.
"The targeting of innocent civilians of any nationality is unconscionable. The United States stands with the government and people of Israel," State Department spokesman Vedant Patel said in a statement.
After years of hostility that fuelled conflicts across the Middle East, Iran and Saudi Arabia agreed to end their diplomatic rift and re-open embassies in a major deal facilitated by China last month.
