United States President Donald Trump on Monday reacted to Iran’s rejection of the US ceasefire proposal, saying that he was very "upset", warning Tehran to pay a "big price."

Trump was speaking to the reporters outside the White House when he said was asked if he would extend the deadline back again. He firmly rejected extension saying the Tuesday deadline for Iran to agree to terms is final.

"Highly unlikely. They've had plenty of time," the United States President said.

"It could end very quickly if they do what they have to do," Trump said. "They have to do certain things. They know that."

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"The people there now are much more reasonable than the lunatics that you had in phase 1 and phase 2," Trump added.

Speaking about negotiations between the US and Iran, Trump said, "I gave them a chance and I hope they take the chance. If they don't, it's trouble."

Trump was responding to the Iranian rejection of the ceasefire proposal of the US. The Islamic regime has rejected the temporary truce and has demanded a complete end to the war with its 10 key demands, including the Strait of Hormuz protocol, commitment towards reconstruction and lifting sanctions.

Although, Trump was upset, he called Iranian proposal "good enough", signalling a possible thaw in reaching a certain level of consensus to at least start considering each other’s terms.

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Trump has warned to make Iran a "living hell" if it fails to strike a deal by 8 pm EDT (0000 GMT) Tuesday. The Trump administration is feeling the heat of the war as Iran has managed to keep the Strait of Hormuz effectively closed since February 28, the start of war.