Iran has the worlds third largest oil reserves. . Yeah they would want that money back that was frozen. Still they have plenty coming in. and they would get it back sooner or later with interest.
Now if people stop buying iranian oil worldwide then that might get their attention.
It was not a matter of whether they would get the money back but only when
Feb 7 - In 2015, Iran reached a historic deal with six world powers to trade curbs on its nuclear programme for sanctions relief, including on oil. But in 2018, the United States under Donald Trump's presidency quit the deal, and sanctions snapped back.