A top Iranian security official accused US President Joe Biden on Saturday of illegally threatening Iran by saying he may consider other options if nuclear diplomacy with Tehran fails.
"The emphasis on using 'other options' against (Iran) amounts to threatening another country illegally and establishes Iran's right to reciprocate ... against 'available options'," Ali Shamkhani, secretary of Iran's Supreme National Security Council, said on Twitter.
Read World Insights: US return to Iran nuclear deal faces standoff
Biden told Israeli Prime Minister Naftali Bennett in White House talks on Friday that he was putting "diplomacy first" to try to rein in Iran's nuclear programme but that if negotiations fail he would be prepared to turn to other unspecified options.
The UN atomic watchdog said in a report this month that Iran had accelerated its enrichment of uranium to near weapons-grade, a move raising tensions with the West as both sides seek to resume talks on reviving Tehran's nuclear deal.
Ignoring pleas by allies, Trump on Tuesday pulled out of an international agreement with Iran that was agreed in late 2015, raising the risk of conflict in the Middle East. Donald Trump's decision to withdraw from the Iran nuclear deal had prompted furious reaction in Tehran, regret in Europe and cheers from Israel and Saudi Arabia.