The official Iranian Railways company is IRIR (or RAI - not the famous Rai). Its main website is the one @chx mentioned - I should correct it does have a tiny (useless) English version though.
A main associate company of RAI is RAJA which comes with a slightly better website . RAJA once completely belonged to RAI (~ until 2010) but now its shares are partially given to another organization due to privatization plans of government.
Why Google doesn't give priority to the RAI main website? ~ Poor (terrible?!) SEO in the English version - if you search in Persian it does recognize the official website: