You move the camera using ScrollTo, either as a behaviour on an object or using the system actions ScrollToX,ScrollToY.
You need to tell the camera to stop scrolling at the appropriate position when your blocking object is on screen. For example:
Blocker is not on screen - Scroll to whatever.X
Blocker is on screen
& distance(whatever.x, whatever.y, blocker.x,blocker.y)>500 - Scroll to whatever.X, whatever.y