Indonesia says it will tighten visa restrictions for visitors from Iran, in one of the first moves in the region aimed at stemming the flow of asylum seekers entering Australia via Indonesia.

The Indonesian Minister for Law and Human Rights has signed a letter preventing people Iranian citizens entering Indonesia from obtaining a ''visa on arrival'' according to the ABC.

The visas can be bought at airports for about $25 and entitle people to stay in Indonesia for 30 days.

Australia has previously lobbied for tighter restrictions on the visas, which it has argued were being used by asylum seekers who fly to Indonesia before travelling to Australia on boats.