Of course, not everyone in the United States reacted in the same way to this attack.  However, the main reaction to the attack was great anger and great patriotic fervor. 

The clearest example of this was the rush by men to volunteer for the armed services in the days after the Pearl Harbor attack.  Recruiting stations were overwhelmed in those days by people wanting to get revenge for Pearl Harbor. 

Another example was the almost complete backing that the idea of war gained among the American people.  Americans had been very reluctant to join WWII before the attack.  After the attack, polls showed that only 2% of Americans opposed American involvement in the war (Source: Bailey, The Home Front: U.S.A, p. 23).

Of course, there was a great deal of trepidation among some people.  There were fears of the consequences that war would bring.  But the overall feeling was that war was the only choice and that essentially all Americans should and would do whatever they could to help win that war.