Heat pump laundry treatment apparatus, in particular a heat pump laundry dryer or a heat pump washing machine having drying function, comprising: a cabinet that houses a rotatable laundry drum for treating laundry using process air, the drum being accessible by a user through a door of the apparatus, a basement which constitutes a bottom portion of said cabinet for supporting operational components for carrying out a drying process on laundry, a process air circuit for circulating the process air through the drum, a heat pump assembly having a refrigerant loop, in which the refrigerant fluid is circulated through a first and a second heat exchanger (15,16), the heat pump assembly comprising a compressing device that is received in a seat formed in the basement and that is removably fixed thereon, and a vibration damping element, wherein the compressing device is fixed to a bottom wall of said basement by a pin which is integrally formed with the basement bottom wall; wherein said pin acts as a support for the vibration damping element extending around the pin and interposed between the pin itself and a base portion of the compressing device; wherein said pin comprises a housing for receiving a screw threadly engaged in said housing, the housing extending along the longitudinal axis of the pin; and wherein said vibration damping element comprise a first end in contact with the base portion of the compressing device and a second end in contact with an upper surface of the basement bottom wall carrying the pin; characterized in that the base portion of the compressing device has an aperture, the pin and the vibration damping element extend through the aperture, and a washer is interposed between, and in contact with, the lower surface of a screw head of the screw and the upper surface of the pin and the vibration damping element. a cabinet that houses a rotatable laundry drum for treating laundry using process air, the drum being accessible by a user through a door of the apparatus, a basement which constitutes a bottom portion of said cabinet for supporting operational components for carrying out a drying process on laundry, a process air circuit for circulating the process air through the drum, a heat pump assembly having a refrigerant loop, in which the refrigerant fluid is circulated through a first and a second heat exchanger (15,16), the heat pump assembly comprising a compressing device that is received in a seat formed in the basement and that is removably fixed thereon, and a vibration damping element, wherein the compressing device is fixed to a bottom wall of said basement by a pin which is integrally formed with the basement bottom wall; wherein said pin acts as a support for the vibration damping element extending around the pin and interposed between the pin itself and a base portion of the compressing device; wherein said pin comprises a housing for receiving a screw threadly engaged in said housing, the housing extending along the longitudinal axis of the pin; and wherein said vibration damping element comprise a first end in contact with the base portion of the compressing device and a second end in contact with an upper surface of the basement bottom wall carrying the pin; characterized in that the base portion of the compressing device has an aperture, the pin and the vibration damping element extend through the aperture, and a washer is interposed between, and in contact with, the lower surface of a screw head of the screw and the upper surface of the pin and the vibration damping element.