Wambach, who is now 35, is scheduled to speak Tuesday night at the University of Kentucky.
She was arrested on Saturday night after running a red light in Portland, Oregon, where she lives, and charged with driving under the influence of intoxicants (DUII) alcohol.
A Portland police spokesman said it is standard for officers to ask about prior drug use. The documents assert that Wambach has never been in treatment for drug or alcohol abuse.
Wambach, a two-time Olympic gold medalist who announced her retirement from the national team in December, posted an apology on her Facebook page Sunday and took responsibility for her actions.
"Those that know me, know that I have always demanded excellence from myself. I have let myself and others down. I take full responsibility for my actions," she wrote. "This is all on me. I promise that I will do whatever it takes to ensure that my horrible mistake is never repeated."
Her attorney, Ben Eder, had no comment following the plea and did not immediately reply to an email seeking comment on the matter. The next court date is April 26.
Wambach went to Twitter on Tuesday afternoon to address the plea of not guilty in light of the Facebook admission: "My lawyer entered a not guilty plea on my behalf. This is standard procedure. I am owning this. Nothing has changed."
Wambach is the leading career scorer male or female in international soccer with 184 goals.
She appeared in four World Cups during her 15 years with the national team. She also has a pair of Olympic gold medals from the 2004 Games in Athens and the 2012 Games in London. She did not compete in the Beijing Games because of a broken leg.
One of Wambach's sponsors, MINI USA, said Sunday night it was withdrawing ads for the automobile that feature Wambach.
"This behavior is against the values we promote as an organization and the safety of everyone on the road is a priority here at MINI. Because of this, we are re-evaluating her association with the brand and are pulling content that individually features Abby from our marketing," the company said in a statement.