I need a script to add border to the placed image

If these are all in one file, or if you are able to use Illustrator actions in a very predictable situation, you could perhaps use effects. Select one or all of your images inside of a file and use the appearance panel to add a new stroke to the placed image. Then inside the same appearance stroke, add a Convert to Shape effect with settings of Relative and use extra height/width parameters which would be close to 0 or at some value where the stroke is hugging your image just right. You can also drag the appearance stroke in front or behind the image to have it overlap or not overlap the image.

You could also use art brushes and multiple strokes to create layered frame components too.

So, doing this manually in one file is alright, but if you have multiple files in folders you can use actions and a pre-made graphic style. When you make a graphic style consisting of your effects, apply it to a random art object and save it in a document and put a note on it so you can select this item via an action later, or ensure this is the only selectable item and then you can use Select-All in an action. (See tutorials on Illustrator actions and selecting via note if you are not aware) This way when you do Actions > Batch process, you can include an action that opens this file each time and copies the item which has the graphic style applied to it. If you select and copy, the document with the graphic style will not be changed and you can use the close command to come back to your real processing document. Then when you are in your image document, find a way to select the placed image and apply your graphic style with an action. The graphic styles are applied via actions by using their name, so as long as your graphic style is named to some string and your action is recorded applying that style, it will work in the documents you wish to batch-process.

Hi,

What is the format of the images. I mean whether they are actual images in format png, jpeg or other format or vector ai files? Could you please share some sample or screen shot how currently they look like and how actually you want.