Yes. For a Publishing site (or a site where the Publishing Feature has been
enabled) go to the Pages document library and hover over the page and from the
contextual drop-down menu select "Manage Permissions". For a non-Publishing
site, that is a Web part page and where you're creating new Web part pages via
the browser, add those pages to a document library/ies and then lock down
permission on the document library/ies.

lets say for eg. a.aspx , i only want user a to edit the content
only. can i set the permission?

may i know what do you mean by add those pages to a document?