Shafaq News/ Iran will not start a war but would "respond strongly" to anyone who tried to bully it, President Ebrahim Raisi said on Friday, a day after the U.S. said it was planning attacks on Iranian sites in Iraq and Syria.

There has been mounting speculation this week about how Washington might retaliate after three U.S. soldiers were killed last Saturday in a strike on their base in Jordan by an Iranian-backed group.

CBS News, citing U.S. officials, reported on Thursday that the United States had approved plans for multi-day strikes in Iraq and Syria against multiple targets, including Iranian personnel and facilities in those countries.

"We will not start any war, but if anyone wants to bully us they will receive a strong response," Raisi said in a televised speech.

"Before, when they (the Americans) wanted to talk to us, they said the military option is on the table. Now they say they have no intention of a conflict with Iran," Raisi said.

"The Islamic Republic's military power in the region is not and never has been a threat to any country. Rather, it ensures security that the countries of the region can rely on and trust," Raisi added.

The United States has assessed that the drone that killed three of its soldiers and also wounded more than 40 other people, was made by Iran, four U.S. officials have told Reuters.

Sources said Iran's elite Revolutionary Guards were pulling senior officers out of Syria.

Iranian advisers assist armed groups in both Iraq, where the U.S. has around 2,500 troops, and Syria, where it has 900.