Iranians have said they cannot charge a "toll" according to international law, but they can charge a "fee". Charging a fee for maintanance, environment or security is fine, so it will be just a different branding to the "toll". Personally I think they should charge an environmental fee with the amount of traffic going through there.

https://www.dawn.com/news/2007544/cannot-impose-tolls-on-str...

They will never charge such a fee, they will however charge a fee and name it "environmental fee".