Baghdad: Two rockets fell on Wednesday inside Baghdad's heavily fortified Green Zone, which houses government buildings and foreign missions, but caused no casualties, the Iraqi military said. Sirens were sounding inside the Green Zone.

Police sources told Reuters at least one of the rockets fell 100 metres (yards) from the US Embassy.

"Two Katyusha rockets fall inside the Green Zone without causing casualties. Details to follow," the military said.Two loud blasts followed by sirens had been heard in Baghdad, Reuters witnesses said.

There was no immediate claim of responsibility.

Iran launched missiles at US forces in Iraq overnight in retaliation for the killing by the United States last week of Iranian General Qassim Soleimani, raising concern about a wider war in the Middle East.

The attack came nearly 24 hours after Tehran launched ballistic missiles at Iraqi bases housing American and other coalition forces, which did not cause casualties.

Meanwhile, Hashed al-Shaabi, a web of armed groups incorporated into the Iraqi state with close ties to Tehran have also vowed to avenge the death of its deputy headAbu Mahdi al-Muhandis along with Soleimani.

Paramilitary chief Qais al-Khazali -- blacklisted as a "terrorist" by the US -- said Iraq's response to the US "will be no less than the size of the Iranian response."

Harakat al-Nujaba, a hardline Hashed faction, vowed to avenge Muhandis.

"To American soldiers: Do not close your eyes. Revenge for the martyr Muhandis is coming at the hands of Iraqis -- until the last soldier among you leaves," it said.

The second attack on US bases in Iraq occured amidst US President Donald Trump's softening stance.

Trump on Wednesday tempered days of angry rhetoric and suggested Iran was "standing down" after it fired missiles at US Forces in Iraq overnight, as both sides looked to defuse the crisis.

(With inputs from Reuters, AFP.)