Was the embargo the cause of the attack of pearl Harbor?

While a major event on the road to war the announcement and enforcement of the Embargo on August 1 was not some sine qua non that if it had been rolled back war might have been averted between the foes.

For +20 years tensions had slowly escalated between the US and Japan over numerous issues. As both sought to further expand their dominance in the Pacific basin,and began to resent the others presence and increasing assertiveness. And even without Oil being the immediate resource the US under FDR was still going to seek to apply its own economic sanctions in response to Japan's ongoing imperial adventure and increasingly bloody war in China, and would support other European powers in doing the same. Scrap metal had already been restricted, and of course any sort of directly militarily useful exports. While by summer of 1941 officers on either side were very clear in their expectation that a Pacific war was coming. This a reckoning of economic, geopolitical, and racial tensions which finally boiled over.

As another point on this, we can say the actual plan of attack was becoming well developed by August of 1941. So separate from the decision to go to war, Yamamoto as the senior sea going admiral had begun floating the plan as his preferred option should war come. In that vein he had begun bringing in trusted experts and staff officers to help work out the problems with the plan, a process which had begun really no later than January of 1941 months before. So it is really two parts of the puzzle, the embargo was a critical step in how war began in late 1941, but without it experts fully expected war to happen over something else. And complimentary regardless of cause Yamamoto fully was committing himself to attacking Pearl Harbor as the opening move, a plan previously considered not worth it or completely impractical.

That said once the Japanese cabinet felt they were faced with the choice of declare war, or be cut off from the resources needed to continue the war in China, or give in and say goodbye to their new Empire and standing, we see why the sought the East Indies. Thats where the resources were!

While Japan got oil from the US, the DEI islands like Borneo represented a far closer source of high quality oil( the modern company Shell can trace part of its history to the Dutch Petroleum company that developed many of these fields and its full name is of course Royal Dutch Shell). The oil from nay of these fields was in many cases good enough to even be burned by ships without refining, though this was not prefered it was done at times by the desperate IJN late in the war.

Japan then was faced with going either North to Siberian fields of oil, and important metals, but face the prospects of renewed conflict with Russia. Or go South and push the colonial powers out and seize the Oil fields, rubber plantations, and other resources while the European powers were concentrated on Europe and they decided on going South. This also included the cornerstone of British power in Asia, the major naval and military base at Singapore on the Malaya Peninsula. These areas were the true objective, Pearl Harbor was simply a move to paralyze their major foe in the US Pacific Fleet, giving time to seize the Southern Resource Area. Which they did in a series of wildly successful campaigns and had secured most targets by the Spring of 1942.