diff --git a/homeassistant/components/google_generative_ai_conversation/conversation.py b/homeassistant/components/google_generative_ai_conversation/conversation.py
index 127ca2cae95..4a93f6ca569 100644
--- a/homeassistant/components/google_generative_ai_conversation/conversation.py
+++ b/homeassistant/components/google_generative_ai_conversation/conversation.py
@@ -81,6 +81,8 @@ def _format_schema(schema: dict[str, Any]) -> dict[str, Any]:
             key = "type_"
             val = val.upper()
         elif key == "format":
+            if schema.get("type") == "string" and val != "enum":
+                continue
             key = "format_"
         elif key == "items":
             val = _format_schema(val)
diff --git a/tests/components/google_generative_ai_conversation/snapshots/test_conversation.ambr b/tests/components/google_generative_ai_conversation/snapshots/test_conversation.ambr
index 7f28c172970..66caf4c7218 100644
--- a/tests/components/google_generative_ai_conversation/snapshots/test_conversation.ambr
+++ b/tests/components/google_generative_ai_conversation/snapshots/test_conversation.ambr
@@ -449,7 +449,6 @@
           description: "Test parameters"
           items {
             type_: STRING
-            format_: "lower"
           }
         }
       }