At least five US personnel were injured in an attack against a military base in Iraq on Monday, US officials told Reuters.
Strikes in Iraq reflect an attempt by Iran to open a new front against the US after several months of quiet in Iraq.
Iran seeks to deepen fault lines in American society and exploit domestic tensions to polarize an already badly polarized society.
Iran is prodding militias to increase threats to the US in Iraq in order to see if the US will pressure Israel not to strike harder at Hezbollah.
Senior US officials said the "suspicious and alarming" information points to computer models that Iranian scientists have made recently can be used for research and development of nuclear weapon.
Iranian caretaker Foreign Minister Ali Bagheri Kani called for the United States to release Afghanistan's frozen assets during the second meeting of the regional contact group for Afghanistan.
The White House also defended its decision to 'official condolences', saying that it was 'typical condolences.'
The new sanctions and other measures will "continue a steady drumbeat of pressure" to contain and degrade Iran's military capacity and effectiveness, National Security Advisor Jake Sullivan said.
Iran's Islamic Revolutionary Guard Corps has said that seven Iranian military advisers died in the strike, including Mohammad Reza Zahedi, a senior commander in its Quds Force.
The US operation was meant to inhibit the Iranian ship’s ability to share intelligence with Houthi militants in Yemen.