Maximum circuit voltage
Use a diode voltage clamp like this:



Due to the diode forward voltage drop the output voltage stays below 4.6V which is more or less what you want. Use a 4volt supply voltage. You can make the reference 4V using a simple voltage divider. 

Also I'm not sure why you're going to do this. The output voltage depends on the amount of the pressure it receives. It can be 0 bars or 2.5 bars. So that doesn't make sense to limit the output at 4.5V. Simply try to avoid measuring pressures greater than 2 bars to stay within the safe limit. 

Since you haven't provided us a datasheet it's not possible to say if it works with a 4.5V input voltage. Read the datasheet and see what it says.