tramp-operation-not-permitted-regexp

tramp-operation-not-permitted-regexp is a variable defined in `tramp.el'.
Its value is

"\\(preserving times.*\\|set mode\\):\\s-*\\(Operation not permitted\\)"

Documentation:
Regular expression matching keep-date problems in (s)cp operations.
Copying has been performed successfully already, so this message can
be ignored safely.

You can customize this variable.