The Stena Impero was traveling through Iranian side of the Strait when it struck an Iranian fishing vessel. The fishing vessel requested assistance from the Impero which ignored them, turned off their tracking system and tried to exit the scene. So yes, the Iranians detained the tanker for violating any number of maritime laws not the least of which being they left another vessel crippled and in danger of sinking in the water. Ergo... no... this is not a 'tit for tat" retaliation for the illegal seizure of that Iranian tanker last week by the British.
Press TV article https://www.presstv.com/Detail/2019/07/20/601393/Iran-UK-oil-tanker-Hormuz-Strait
TASS News article https://tass.com/world/1069566
TASS News article https://tass.com/world/1069576
To support my work you can contact me via email to get my snail mail address or you can help thru Patreon (till they shut that down like they did my Paypal account)