is there any way to get my possesion of cannabis case dropped

I was in a parking area behind my friends house doing some work on a vehicle. Lot is private property. Police came and said there was a call for a man with a gun. I didn't have a gun nor did any one around me. They cuffed me up and looked everywhere for a gun but came up unsucessful. But in process found a tobacco pipe with marijuana in my car. Now my car was closed no keys in ignition but Windows were open. I don't see why I have been point of interest because they even stated that I wasn't described in the call. There has got to b a way I can get this dropped thru probable cause or private property or something