Use the 
Mask area feature in 
Security Monitor Pro to block off monitoring for motion from a selected area. 
To 
add a mask, click the 
Manage Camera icon on the toolbar. Select the camera and click the 
Edit Camera button. Go to the 
Mask Area tab and select the 
Enable Masking checkbox. Adjust the shape of the mask according to your requirement by clicking on the box and dragging it. Add additional masks for the areas you don't want to monitor. Click the 
OK button to save your changes. 

Once you put a mask on the camera preview, start motion detection monitoring. Notice how motion behind the masked region will not get detected. This will reduce the possibility of unwanted triggering of alerts.