Iran's Islamic Revolutionary Guard Corps warned on Thursday that "the aggressor will be punished today," According to the country's state news agency IRNA.
The IRGC stated that any nation providing military assistance to the United States would face a "harsh response."
That morning, Iran launched missiles and attack drones at Jordan and Kuwait, both countries confirmed.
In Kuwait, the strikes hit a facility operated by a Chinese company in the northern part of the country, the defense ministry said. One worker was killed and the site sustained "significant" Damage.
Jordan's military said air defenses successfully intercepted five Iranian ballistic missiles. The interception occurred "efficiently and professionally," A military source told the Petra News Agency, with no casualties reported.
Separately, Egypt's government said an investigation found that a drone sparked fires on two ships at Damietta Port on the Mediterranean coast in the Nile Delta the previous day.
While no group claimed responsibility, Iranian sources told The New York Times the strike was "designed to show that global shipping and energy supplies could be more deeply disrupted if Iran chose to escalate." Tehran is widely believed to have carried out the drone attack.