Depends on the source, but it should be possible to do.
You need to apply to World Ready composer, and change the direction of the text to RTL (from LTR that English and other Euro languages use).
One way is to do the following:
1. Make a text frame
2. Hold down Command/Ctrl key and go to Type > Fill with Placeholder text. You will then get a dialog that lets you choose language. Choose Arabic
3. Copy your text, then select all the Arabic placeholder text, and paste.
Your text should hold the Arabic formatting correctly.