These two conditions - a guarantee that [country] will not be attacked again; a permanent end to the war, not just a ceasefire - is quite similar to the conditions Russia/Ukraine want to end their war. So it's a reasonable guess that Iran is seeking something similar to what Ukraine is seeking, which is peacekeepers from more powerful countries. The idea is that if there are French & UK (and possibly other countries') soldiers on the ground, then a new invasion by Russia would trigger retaliation from these nuclear-armed countries.
Presumably Iran would seek peacekeepers from China/Russia, maybe Pakistan/India.
NB: This is speculative right now; no details have emerged (that I have seen, at least). Iran is also not Ukraine - thus far it is fighting mostly alone, and it has historically refrained from joining military alliances. They might be looking for something else than foreign troops on their soil.
Edit: Iran has apparently asked China for security guarantees. China has not and apparently is not likely to accept, although they did guarantee the security of Iran's diplomats.
Underscoring the risks, Pakistani officials reportedly told the Guardian that while Islamabad acted as mediator in recent talks, China functioned as “guarantor,” promising Iranian officials they wouldn’t be assassinated during any future negotiations. It’s unclear how Beijing would offer such an assurance, or the motivation for doing so given the repercussions should something then go wrong.
...
Bringing Iran to the negotiation table, however, is only the first step to end hostilities. Tehran is seeking security guarantees that it won’t be attacked again, and has publicly asked Beijing to play such a role — a request analysts say China is unlikely to accept.