Building new efficient and power engines did not come easy or cheap... Russia has invested a lot of time and money and effort into making its own jet engines and over the last decade and a half has been developing its own series of related new technology new design jet engines that are only getting ready for final testing now or only just ready for serial production.
Russia likely wants Iran to succeed and grow and develop because stable growing countries are less interested in war and conflict and both sides can help each other, but equally Russia does not want to hand everyone technology it has mastered just like that...
I rather suspect licence production and also perhaps setting up overhaul and repair sites in Iran to service other countries in the region would be a good start and also allowing them to licence produce serial airliners of different sizes and shapes... smaller aircraft preferably because they are needed in large numbers in Russia and once the Russian market is satisfied the export market is going to be quite big too so help with supporting that makes sense.
If they can do this , then they can reverse Engineer military jet engine . They are test flying stealth jet planes , what engine ? Well they may have an F16 from Iraq ...no licence needed ! But Russia can give secret recipes instead ?
I suspect Russias preference would be that Iran (amongst others) join the Checkmate programme and end up locally producing their own aircraft with features adapted to their preferences and desires, and I would expect the engine that goes with that would be the current engine in the Su-57 which should be OK to export.
It will of course be your plane so there wont be restrictions on it like US plane agreements which are more like Leases than purchase agreements.
Iran could also work with China if they want to go that way too and Russia is not going to punish Iran if that is what they end up doing.
Reverse engineering is difficult, and to be able to do it means that the Iranian aerospace industry progressed a lot.
It is quite interesting though, because design companies are often out of touch with the latest fabrication methods and so their descriptions and instructions on making their aircraft might work, but once the factory that makes them gets their hands on the design and has made a first batch, often there are improvements they can add and changes to the official design they can make to make the plane faster and easier and cheaper to make without breaking the design.
A lot of innovation actually happens on the factory floor, which means that even with reverse engineering... in face because of reverse engineering the Iranians have had to problem solve rather more than a western or even Russian fabricator who is handed the plans and the specs and is just expected to build it.
This has been shown in Russia with the Ansat helicopter which is a light helicopter that was not designed and built by Mil or Kamov or even Yakovlev.... it was designed by a factory that made helicopters and it just designed its own.
A builder who has a decade or more of experience in building and repairing and fixing houses will have a good idea of what materials last longest and what is low maintenance and what is high maintenance and what is value for money and might even be able to design a more comfortable home than some architect straight from college who wants to make his mark with something unique and interesting.
Anyway this engine has probably many components in common with the modernised versions of it, and that means that Iran can probably also produce spare parts for the engines of the 737 and a320 currently still in service with russian airlines.
Which explains the ties with Russia as Iran would be an ideal place to service most of Russias foreign airliners while they remain in service... something Iran has been doing for itself for some time now.