Why did Iran take the British hostage?

There is always a reason why things are done in the world of international politics. Apparently Iran was upset with American attempts to take a few Iranians hostage so they retaliated.

The botched US raid that led to the hostage crisis

"Better understanding of the seriousness of the US action in Arbil - and the angry Iranian response to it - should have led Downing Street and the Ministry of Defence to realise that Iran was likely to retaliate against American or British forces such as highly vulnerable Navy search parties in the Gulf. The two senior Iranian officers the US sought to capture were Mohammed Jafari, the powerful deputy head of the Iranian National Security Council, and General Minojahar Frouzanda, the chief of intelligence of the Iranian Revolutionary Guard, according to Kurdish officials."