They desperately need some sanctions relief - just not desperately enough yet.
I guess they are afraid that if the sanctions are not lifted soon, it will be a very cold, starving winter for the Iranian people and that will likely mean riots and revolution before spring.
It must have been crushing for Iran to find that France, Germany, UK and others all agree that Iran despite its lies is blamed for the Saudi oil refinery bombing. After the leaders agreed it was Iran that did the deed, they will have little choice be to agree to any additional sanctions imposed by the USA or have their businesses face the wrath of US economic sanction.