Iranian officials have often expressed hostility towards Israel. They don't want Israel to be present in the region and have even predicted a time when Israel will collapse. The U.S. has a responsibility to its allies, and sanctions help to constrain governments that do not align with U.S. policies.
It is also widely believed that Iran provides financial and military support to several proxy groups—such as Hamas, the Houthis, and Hezbollah—that are committed to the annihilation of Israel.