Some facts to add
I was quite impressed by many of the comments and facts given in the comments so far. There are many 'facts' quoted in the media which are inaccurate or misleading. I live in the UK but have Iranian friends and have read quite a lot about Iran's history and these recent events.
Firstly, the price increase is more than just the 50% quoted by some. I believe the price was 1000 toman ( a toman is 10 rial) per litre before for 120 litres per month (I am unsure of the price after that). Now the subsidised amount has been reduced by 50% to 60 litres per month and the price for that raised to 1500 toman. After that the price increases to 3000 toman. That is a 300% rise for the 60 litres that used to be at the lower subsidised rate and no doubt still a big increase over the previous higher rate.
Whilst the media state this is only a few cents per litre and state it is very cheap they are quoting against the free or black market rate for currency exchange which is 3 times lower/higher depending on whether you are buying or selling than the official rate. The official rate the government quote is not available to the general population. As some have stated the costs of fuel is all relative to their income and available funds. Whilst some in Iran are very rich and there are loads of expensive thirsty cars, most people are poor and paid maybe just 10 dollars a day and are struggling to afford to live and feed their families. I went to Argentina in 2002 when their financial crash happened and the Peso plunged against the Dollar etc. We ate at a 'All you can eat Restaurant' for about £1.25 per adult which was less than 2 Dollars and incredibly cheap to us. However, I spoke to an Englishman in there who lived and worked there and he said it was expensive to them.
When I went to the US and petrol/gas there was half the price of the UK (we currently pay about $6.20 per US Gallon/3.8 Litres) people we spoke to said they wouldn't pay our prices. The answer is they would if they had to but they would start to think more about fuel efficiency like most here have to.
Yes, the situation in Iran is bad due to an oppressive regime (more asylum seekers have come to the UK from Iran than from any other country in recent years) but this is not helped by the mistreatment and exploitation that has happened by the West, especially the UK and USA. Donald Trump and his cronies are the worst in a long time and bringing shame on the USA and are causing the greatest danger to the world at present I believe. Unfortunately we have mini- Trump in UK. As they say, we get the Government we deserve!