White's detention adds new pressure to the rising tension between Iran and the US, which under Trump has pursued a maximalist campaign against Tehran that includes pulling out of its nuclear deal with world powers.
Efforts for a negotiated settlement of the 18-year-old war in Afghanistan have gathered pace in recent weeks, even as reports that U.S. President Donald Trump plans to withdraw thousands of U.S. troops have triggered uncertainty in Kabul.
Washington gave Iraq a 45-day waiver over imports of Iranian gas when it reimposed sanctions on Iran's oil sector on Nov. 5. Iraqi officials have said they need around two years to wean themselves off Iranian gas imports and find an alternative source.
"Three people were killed and some others were injured," Chabahar's acting governor Rahmdel Bameri told state television. An official told TV that "the terrorist who carried out the attack was killed".
"The sanctions have had no impact on our economy because America had already used all the weapons at its disposal and there was nothing new to use against us," Hassan Rouhani said in remarks carried live on state television.