Iran appeared to launch missiles toward US military bases in Jordan, according to local and Iranian media reports.
The reports said early on Wednesday that the missiles were fired toward US installations in the country, with air defence systems trying to intercept the incoming projectiles.
US publication Axios cited a US official as saying that the missiles were intercepted.
In a statement, the US Central Command said that Iran's Revolutionary Guards launched missiles against US forces based in the region, without specifying the location.
"Islamic Revolutionary Guard Corps forces launched multiple ballistic missiles from Iran in an attempted surprise attack on U.S. forces based in the Middle East," CENTCOM said.
"All Iranian missiles were successfully intercepted. U.S. forces remain vigilant and at a high state of readiness."
On high alert
Both sides had held fire over the weekend, following nearly two weeks of nightly strikes by the US on Iran, and repeated missile and drone salvos by Tehran targeting Washington's allies around the Gulf.
The mid-July flare-up in fighting came after several ships were hit in the Strait of Hormuz.
Oil prices had plummeted following the weekend lull in fighting and as US President Donald Trump said there was a "good chance" of progress in negotiations to end the war.
Tensions between the US and Iran have escalated in recent weeks, with Washington carrying out attacks on Iran and Tehran responding by targeting what it says are US military facilities and equipment in countries across the region.
