A defendant who claims to be innocent but doesn't want to risk going to trial can sometimes take what has become known as an Alford plea, named after the Supreme Court's decision in North Carolina v. Alford. (400 U.S. 25 (1970).) Although the Supreme Court in Alford held that a plea of guilty by someone who claims to be innocent doesn't violate the Constitution, it also held that states could make their own laws regarding such pleas.
Alford pleas, like guilty and nolo contendere or "no contest" pleas, result in conviction. Some states allow classic Alford pleas, where defendants plead guilty while claiming to be innocent. Others require a defendant who claims innocence to plead no contest. Others still don't allow Alford pleas at all: In those states, if you assert innocence, you must plead not guilty.
It's very important to seek the advice of an attorney before accepting any type of plea deal. Laws regarding the available pleas, their requirements, and their implications vary from place to place. An attorney familiar with the laws of your jurisdiction will be able to help assess your options.