"the EU" can speak only in treaties, and so has not spoken yet.
But yes, multiple people connected with the EU government have been making statements to this effect: out means out. It is not in the EU's interest to give the UK a more favourable deal than it had before, because that signals to other member countries that leaving has financial benefits.
A more favourable deal than the UK already had is indeed unlikely, because the UK already had an unreasonably sweet deal. But I really do hope the EU will give the UK a fair deal in the coming negotiations. There's no point in needless hostility. Unless they want to make good on that World War 3 scare.
But yes, multiple people connected with the EU government have been making statements to this effect: out means out. It is not in the EU's interest to give the UK a more favourable deal than it had before, because that signals to other member countries that leaving has financial benefits.