The concept of De Broglie wavelength does not form a part of classical mechanics.You may take it as a rule of thumb that such concepts can only be applied to microscopic particles to get practical results. Even though these properties are present in macroscopic particles also, it is not humanely possible to observe them.
Coming to the exact reason,
De Broglie wavelenghth of a moving particle= Planck’s constant/Momentum of the particle= Planck’s constant/(Mass of the particle x velocity of the particle)
So, as you can see, for particles which macroscopic(i.e., relatively massive) the De Broglie wavelength is very less and the wave like characteristics are diminished to a certain extent(that is, not observable).