The reduced commitments Iran is talking about are: Quit the selling of excess uranium and D2O (heavy water) which was mentioned in the deal. The main reason for this, is that in particular the EU nations in the nuclear deal, have not met their part of the agreement and thus UN resolution 2231 made in 2015.
https://en.wikipedia.org/wiki/United_Nations_Security_Council_Resolution_2231
Iran emphasized that the deal can work without the United States and that the countries involved have to play their part and not allow themselves to be threatened by one sided US sanctions which are created to make them too withdraw completely from the deal or not abide by both the P5+1 deal and UN resolution. Iran has therefor still till this very day upheld every obligation under the deal
https://www.rferl.org/a/iaea-iran-compliance-2015-nuclear-deal/29461841.html
but has taken these measures with what they call a '60 day window', to allow the EU nations in the nuclear deal to finally uphold their part of the agreement, so Iran will start doing the same again.
https://www.presstv.com/Detail/2019/05/08/595397/Iran-change-commitment-nuclear-deal-JCPOA-Rouhani-letter
In my opinion, this is a make or break point for both the Iran nuclear deal, and EU independence from the 'Dollar dictatorship'.