Fire itself is energy being released from atomic bonds; since it is energy and not matter, you cannot classify it this way. However, your question is interesting in that, in order for there to be a fire, matter must be present, and often a change of state is involved.
A fire must have fuel with energy-rich atomic bonds (usually in the form of a carbohydrate of some sort) and oxygen to support the combustion reaction. The fuel can be in the form of a solid, liquid, or a gas. In the case of a solid or liquid fuel, the fuel usually will not burn readily unless it is converted into the gaseous state. For instance, in order for a candle to burn, the solid wax must melt and travel up the wick. The liquid wax in the wick, upon coming close to the flame, transitions to the volatile gas phase, which is then burned. In the case of liquid fuels like gasoline, the liquid must either evaporate into the gas phase or else be sprayed as a fine mist in order to burn.