to do...i.e. weaken America both domestically and internationally...and he certainly didn't want the U.S. and Iran to normalize relations....for further evidence search for the Atlantic Council article entitled "Russia secretly feared the Iran nuclear deal...Here's why"
btw, Iran is not 100% behind the regime currently in charge...it is not a monolith politically, by any means.
Link: https://www.armscontrol.org/act/2019-04/news/iaea-says-iran-abiding-nuclear-deal