The newly appointed commander of Iran's elite Quds Force said the United States killed his predecessor, Qassem Soleimani, "in a cowardly way" and promised to "hit his enemy in a manly fashion".

Esmail Qaani made the remarks on Monday at an introduction ceremony held for him by top Islamic Revolutionary Guard Corps' (IRGC) commanders to mark the formal beginning of his tenure.

"They (US) hit him (Soleimani) in a cowardly way, but with God's grace and through endeavours of freedom-seekers around the world who want vengeance over his blood, we will hit his enemy in a manly fashion," he said.

Soleimani's assassination in a US air strike in Baghdad on January 3 pushed the US and Iran to the brink of war, but fears of an all-out conflict eased when retaliatory Iranian attacks against US targets in Iraq on January 8 concluded without any fatalities.

Iran's Supreme Leader Ali Hosseini Khamenei has since called for the expulsion of all US troops from the Middle East.