Can we develop Groovy Script on Purchase Requisition Page

We have a requirement to restrict few project tasks(not projects) in requisition page. We couldn't do it with any configuration. so we are thinking of technical approach. In our case all the tasks which to be restricted starts with the name 'Conversion'. So we are planning to develop a Groovy script which gives an error message whenever user chooses the task starting with word 'Conversion'.

Does oracle application support Groovy script for this feature in Requisition page ?

Ex: I can create a requisition against a project/task. Here I will enter project, task, expenditure type, expenditure org, expenditure date in the requisition page. I don't want a particular task to be shown in this screen.