The gathering coincided with increasing tensions between Iran and the United States in the last days of President Donald Trump's administration, and many in the crowd demanded revenge.
"Be careful of a trap, @realDonaldTrump. Any fireworks will backfire badly, particularly against your same BFFs," Zarif wrote, in what appeared to be a veiled threat against Israel.
U.S. officials blame Iran-backed militia for regular rocket attacks on U.S. facilities in Iraq, including near the embassy. No known Iran-backed groups have claimed responsibility.
Analysts said the secondary sanctions may further deter European and other foreign banks from working with Iran, even for permitted humanitarian transactions.
But the other parties to the nuclear deal - Britain, China, France, Germany and Russia - and most of the U.N. Security Council have said they do not believe the ...
Given questions over the U.S. move, diplomats said Russia, China and other countries are likely to simply ignore it and not reimpose the sanctions on Iran.