diff --git a/pandas/tests/series/test_constructors.py b/pandas/tests/series/test_constructors.py
index 36a581a8ca492..22076eb05db88 100644
--- a/pandas/tests/series/test_constructors.py
+++ b/pandas/tests/series/test_constructors.py
@@ -1390,10 +1390,14 @@ def test_constructor_cast_object(self, index):
         tm.assert_series_equal(s, exp)
 
     @pytest.mark.parametrize("dtype", [np.datetime64, np.timedelta64])
-    def test_constructor_generic_timestamp_no_frequency(self, dtype):
+    def test_constructor_generic_timestamp_no_frequency(self, dtype, request):
         # see gh-15524, gh-15987
         msg = "dtype has no unit. Please pass in"
 
+        if np.dtype(dtype).name not in ["timedelta64", "datetime64"]:
+            mark = pytest.mark.xfail(reason="GH#33890 Is assigned ns unit")
+            request.node.add_marker(mark)
+
         with pytest.raises(ValueError, match=msg):
             Series([], dtype=dtype)
 
diff --git a/pandas/tests/series/test_dtypes.py b/pandas/tests/series/test_dtypes.py
index 05e708e575a64..bcc0b18134dad 100644
--- a/pandas/tests/series/test_dtypes.py
+++ b/pandas/tests/series/test_dtypes.py
@@ -382,11 +382,15 @@ def test_astype_categoricaldtype(self):
         tm.assert_index_equal(result.cat.categories, Index(["a", "b", "c"]))
 
     @pytest.mark.parametrize("dtype", [np.datetime64, np.timedelta64])
-    def test_astype_generic_timestamp_no_frequency(self, dtype):
+    def test_astype_generic_timestamp_no_frequency(self, dtype, request):
         # see gh-15524, gh-15987
         data = [1]
         s = Series(data)
 
+        if np.dtype(dtype).name not in ["timedelta64", "datetime64"]:
+            mark = pytest.mark.xfail(reason="GH#33890 Is assigned ns unit")
+            request.node.add_marker(mark)
+
         msg = (
             fr"The '{dtype.__name__}' dtype has no unit\. "
             fr"Please pass in '{dtype.__name__}\[ns\]' instead."