forms.py:
class OnlyActiveAuthenticationForm(AuthenticationForm):
    def confirm_login_allowed(self, user):

        if user.state == 'deactivated':
            raise forms.ValidationError(_(u'Tento účet je deaktivovaný, kontaktujte správce Vaší firmy'),
                                        code='deactivated',
            )
urls.py:
from django.contrib.auth.views import login
url(r'^login/$', login, {'authentication_form': OnlyActiveAuthenticationForm}, name='login'),