Before the war started there was no threat to blockade the straits of Hormuz, now one exists. 20% of the worlds oil passses through that strait. They are also able, if they are attacked to put out of action the middle east countries oil and Gas production. They have already shown they are prepared to attack those installations. Thousands of bombs were dropped on them, but it did not stop them having the ability to disrupt the fuel and energy supply the world desperatley needs.
Trump statrted the war fully supporting their strong regional ally Israel. Now, because Iran has linked ending the war to what goes on, in Lebonon, he is putting huge pressure on Israel to stop attacking Lebonon. He won't get Iran to give up its nuclear enrichment.
And finally, despite the bluster it has been Trump the more desperate for a deal. The Iranian regime is prepared to suffer far more than trump is in a war, their goal is simply to survive, and they have.
They truly believe they won the war