So I read from different places different reasons given to the Japanese attack of pearl harbour. Wether it was retaliation against USA cutting oil export, or japan trying to destroy the Pacific fleet that would offer resistance towards the Japanese conquest of Southeast Asia. So was it both, more?
Not to discourage other answers but there are a number of articles about the reasons for, and the events leading up to, the attack on Pearl Harbor in the /r/askhistorians FAQ :
https://www.reddit.com/r/AskHistorians/wiki/faq/militaryhistory/wwii/fronts#wiki_pearl_harbor
Specifically :
https://www.reddit.com/r/AskHistorians/comments/2r7i4c/why_did_japan_attack_pearl_harbor/cndiyuu/
I believe that article answers your basic question.
It's important to note that the attack on Pearl was only one part of a massive plan which entailed the conquest of practically all of the Western Pacific from the Philippines to Indonesia. It was the need to deter the US from interfering with this plan that drove the decision to attack the US fleet.
If you have additional questions ask away ...