diff --git a/google/genai/_api_client.py b/google/genai/_api_client.py
index bb9865cc4..a8bddbecd 100644
--- a/google/genai/_api_client.py
+++ b/google/genai/_api_client.py
@@ -2101,7 +2101,9 @@ async def aclose(self) -> None:
     """Closes the API async client."""
     # Let users close the custom client explicitly by themselves. Otherwise,
     # close the client when the object is garbage collected.
-    if not self._http_options.httpx_async_client:
+    if not self._http_options.httpx_async_client and getattr(
+        self, '_async_httpx_client', None
+    ):
       await self._async_httpx_client.aclose()  # type: ignore[union-attr]
     if self._aiohttp_session and not self._http_options.aiohttp_client:
       await self._aiohttp_session.close()