@Mehran25 If you would rather have long term guests rather than short term, increase your nightly rent and then add a discount on the monthly rent. For example $200 per night ($6000 for 30 nights) but if renting for 30 nights or more, add a 20% discount =$6000 less $1200 equals $4800 (or $160 per night).
I do not recommend using AirBnB for long term rentals until you are accustomed to the platform and hosting. Depending on your location, renting for more than 30 days may qualify the guest as a tenant. AirBnB is best suited for rentals of less than 14 days. If you want to be a long-term rental property, use a realtor that specializes in qualifying long-term tenants.