US ambassador Kelly Craft told the U.N that the Trump administration was 'ready to engage without preconditions in serious negotiations with Iran'.
Craft cited Article 51 of the U.N. Charter while justifying the killing of general Soleimani.
Iran's supreme leader Ayatollah Ali Khamenei said the missile strikes was a 'slap in the face' for America.
After President Trump in a televised address to the nation said Iran appeared to be standing down after the missile strikes on US bases, the United States informed the UN that the assassination of Iran general Qasim Soleimani was an act of "self defense".
US ambassador Kelly Craft told the United Nations that the Trump administration was "ready to engage without preconditions in serious negotiations with Iran, with the goal of preventing further endangerment of international peace and security or escalation by the Iranian regime."
Craft cited Article 51 of the UN Charter while justifying the killing of general Soleimani stating clearly that "the United States is prepared to take additional actions in the region as necessary to continue to protect U.S. personnel and interests."
The US ambassador further said that US airstrikes on Iraq and Syria last month and the killing of Soleimani was "in response to an escalating series of armed attacks in recent months by the Islamic Republic of Iran and Iran-supported militias on US forces and interests in the Middle East."
Meanwhile, Iran's ambassador to the UN, Majid Takht Ravanchi, in a letter to the United Nations said his country has full respect for "the independence, sovereignty, unity and territorial integrity of the Republic of Iraq", a day after conducting the ballistic missile strikes on US bases in Al-Asad and Irbil.
"The operation was precise and targeted military objectives thus leaving no collateral damage to civilians and civilian assets in the area," Majid Takht Ravanchi said in a letter to the UN.
Tensions between Iran and US mounted on Wednesday after Teheran carried out multiple strikes on US bases, however, there was no report of any US casualties. The Iraqi government also clarified no lives were lost in the strikes.
After the ballistic missile strikes, Iran's supreme leader Ayatollah Ali Khamenei said the missile strikes was a "slap in the face" for America.
"Military action like this is not sufficient. What is important is ending the corrupting presence of America in the region," he said.
"Today Iran is well equipped," Khomeini said, adding, "More people will join the movement and it will spread outside Iran."
"The US thought they defeated Iraq," he said. "Faith allows us to move mountains," the supreme leader said at a public gathering.
"Faith and honour are as important as the military," Khomeini said.