diff --git a/django/db/backends/postgresql/introspection.py b/django/db/backends/postgresql/introspection.py
index 82013eb19113..fc69e0a381e1 100644
--- a/django/db/backends/postgresql/introspection.py
+++ b/django/db/backends/postgresql/introspection.py
@@ -206,7 +206,9 @@ def get_constraints(self, cursor, table_name):
                 cl.reloptions
             FROM pg_constraint AS c
             JOIN pg_class AS cl ON c.conrelid = cl.oid
-            WHERE cl.relname = %s AND pg_catalog.pg_table_is_visible(cl.oid)
+            WHERE cl.relname = %s
+                AND pg_catalog.pg_table_is_visible(cl.oid)
+                AND c.contype != 'n'
         """,
             [table_name],
         )
diff --git a/tests/migrations/test_base.py b/tests/migrations/test_base.py
index b636d18ec414..24ae59ca1b9a 100644
--- a/tests/migrations/test_base.py
+++ b/tests/migrations/test_base.py
@@ -108,6 +108,7 @@ def assertIndexExists(
                     .values()
                     if (
                         c["columns"] == list(columns)
+                        and c["index"] is True
                         and (index_type is None or c["type"] == index_type)
                         and not c["unique"]
                     )