diff --git a/pandas/_libs/tslibs/conversion.pyx b/pandas/_libs/tslibs/conversion.pyx
index 0076ec74ea9e1..9964ca0847ce7 100644
--- a/pandas/_libs/tslibs/conversion.pyx
+++ b/pandas/_libs/tslibs/conversion.pyx
@@ -1045,6 +1045,10 @@ def normalize_date(object dt):
     Returns
     -------
     normalized : datetime.datetime or Timestamp
+
+    Raises
+    ------
+    TypeError : if input is not datetime.date, datetime.datetime, or Timestamp
     """
     if PyDateTime_Check(dt):
         if not PyDateTime_CheckExact(dt):
@@ -1063,7 +1067,7 @@ def normalize_date(object dt):
 
 @cython.wraparound(False)
 @cython.boundscheck(False)
-def date_normalize(ndarray[int64_t] stamps, tz=None):
+def normalize_i8_timestamps(ndarray[int64_t] stamps, tz=None):
     """
     Normalize each of the (nanosecond) timestamps in the given array by
     rounding down to the beginning of the day (i.e. midnight).  If `tz`
diff --git a/pandas/_libs/tslibs/timestamps.pyx b/pandas/_libs/tslibs/timestamps.pyx
index 401ba76e341b2..711db7cc8fbe2 100644
--- a/pandas/_libs/tslibs/timestamps.pyx
+++ b/pandas/_libs/tslibs/timestamps.pyx
@@ -21,7 +21,7 @@ from util cimport (is_datetime64_object, is_timedelta64_object,
                    INT64_MAX)
 
 cimport ccalendar
-from conversion import tz_localize_to_utc, date_normalize
+from conversion import tz_localize_to_utc, normalize_i8_timestamps
 from conversion cimport (tz_convert_single, _TSObject,
                          convert_to_tsobject, convert_datetime_to_tsobject)
 from fields import get_start_end_field, get_date_name_field
@@ -1083,7 +1083,7 @@ class Timestamp(_Timestamp):
         Normalize Timestamp to midnight, preserving
         tz information.
         """
-        normalized_value = date_normalize(
+        normalized_value = normalize_i8_timestamps(
             np.array([self.value], dtype='i8'), tz=self.tz)[0]
         return Timestamp(normalized_value).tz_localize(self.tz)
 
diff --git a/pandas/core/indexes/datetimes.py b/pandas/core/indexes/datetimes.py
index 05f7af6383211..966eff58262e8 100644
--- a/pandas/core/indexes/datetimes.py
+++ b/pandas/core/indexes/datetimes.py
@@ -2002,7 +2002,7 @@ def normalize(self):
                        '2014-08-01 00:00:00+05:30'],
                        dtype='datetime64[ns, Asia/Calcutta]', freq=None)
         """
-        new_values = conversion.date_normalize(self.asi8, self.tz)
+        new_values = conversion.normalize_i8_timestamps(self.asi8, self.tz)
         return DatetimeIndex(new_values,
                              freq='infer',
                              name=self.name).tz_localize(self.tz)
diff --git a/pandas/tests/tslibs/test_api.py b/pandas/tests/tslibs/test_api.py
new file mode 100644
index 0000000000000..387a63f61179d
--- /dev/null
+++ b/pandas/tests/tslibs/test_api.py
@@ -0,0 +1,37 @@
+# -*- coding: utf-8 -*-
+"""Tests that the tslibs API is locked down"""
+
+from pandas._libs import tslibs
+
+
+def test_namespace():
+
+    submodules = ['ccalendar',
+                  'conversion',
+                  'fields',
+                  'frequencies',
+                  'nattype',
+                  'np_datetime',
+                  'offsets',
+                  'parsing',
+                  'period',
+                  'resolution',
+                  'strptime',
+                  'timedeltas',
+                  'timestamps',
+                  'timezones']
+
+    api = ['NaT',
+           'iNaT',
+           'OutOfBoundsDatetime',
+           'Timedelta',
+           'Timestamp',
+           'delta_to_nanoseconds',
+           'ints_to_pytimedelta',
+           'localize_pydatetime',
+           'normalize_date',
+           'tz_convert_single']
+
+    expected = set(submodules + api)
+    names = [x for x in dir(tslibs) if not x.startswith('__')]
+    assert set(names) == expected