The reason Japan attacked the US even tho both countries were not involved in the war at the time was because of oil. The US was buying up the surplus oil and driving up the price. Japan could not keep up with the rising prices, and attacked us for trying to destroy their economy. So no. If there hadn't been a war already in progress, limiting resources, Japan would not have attacked.
Like most of the comments in here Pearl Harbor is what got us in the war and after they had done this the general who commanded the attack had realized by Attacking the U.S he had awakened a sleeping Giant that is The United States
The US blocked many of Japan's trade dealings with other Asian countries. The confrontation "would have come to a head" at some point, most likely at the US's naval yard in the pacific. Those who can't negotiate with words, resort to force. Look at how Japan "raped" throughout Asia, both figuratively and literally.
We would have had to find some other reason - or orchestrate one on our own - to justify dropping atom bombs on civilian populations - to define us as the world's unbeatable super-power. Japan's "Pearl Harbor" event was exactly quoted by Cheney and his neocon buddies as to what would be needed to gain national support for an attack to decimate and rebuild (American Imperialism) Iraq - confusion of the public would be part of the plan as to whom had actually attacked us (hint: not Iraq - we had the country under lock and key with no-fly zones and our intelligence agents everywhere in the country). How fortuitous for the neocons that 9/11 was exactly the "Pearl Harbor" like event needed to institute the "Bush Doctrine" of pre-emptive invasions - no wonder they refused to listen to Clinton's outgoing security briefings - especially the one that read, "hijacked commercial airliners will be used as missiles to attack skyscrapers in New York City" (a "Pearl Harbor" event). They even had the gaul to detail all of this in their neocon "Project for a New American Century" - written long before they had attained the power to carry it out.