How do you think it would be if...

As I understand it, the embargo was to curtail the agressive Japanese in other Asia countries. Correct me if I'm wrong here. I would suspect all trade would stop after ships are sunk.

No, there were threats from countries about stopping trade with Japan because of the attacks on those countries trade with China but little actually happened for a coupe of years until they got really pissed off with the Japanese. Generally Japan would apologise, offer compensation and everyone was happy....till next time when Japan would apologise.....

It got complicated due to the legal limbo created both by the sino-japanese treaty and the failure to declare a state of war.
Under the 19th century treaties America, Italy, Portugal, France and Britain (and later Japan) protected shipping and guaranteed safe passage all the way from shanghai to chungking(and beyond in theory). Japans attempt after siezing the lower river to restrict that shipping and stop Chinas trade was illegal as due to her own treaty obligations and as the inheritor of German trade rights she had to guarantee free passage too.

Really it can't be put any other way, Americas eventual embargo was not a provocation, it was a very mild very delayed reaction to repeated and sustained provocations by Japan.