U.S. Secretary of State Mike Pompeo on Sunday said Washington was ready to negotiate with Iran with "no pre-conditions".
Pompeo, who is currently in Switzerland for official talks, was speaking at a joint news conference with his Swiss counterpart Ignazio Cassis.
He called on Tehran to spend its resources to meet the basic needs of the Iranians, saying Iran's activities in Syria have led to displacement of some 6 million people across war-weary Syria.
He went on to say that the political and economic pressure on Iran would continue.
On May 29, Iranian President Hassan Rouhani said: "The door of negotiations is not closed provided the U.S. lifts the sanctions and fulfills its commitments."
Tensions between Iran and the U.S. have mounted steadily since 2017, when U.S. President Donald Trump withdrew his country from a landmark nuclear agreement between Tehran and the P5+1 group of nations (the five permanent UN Security Council members plus Germany).
Since then, the Trump administration has also re-imposed sanctions on Iran’s banking and energy sectors, while Iran has threatened to close the strategic Strait of Hormuz to U.S. oil shipments.
By Ali Murat Alhas