diff --git a/backend/open_webui/main.py b/backend/open_webui/main.py
index ecba6407f3..0f9d455136 100644
--- a/backend/open_webui/main.py
+++ b/backend/open_webui/main.py
@@ -1888,6 +1888,9 @@ generate_chat_completions = chat_completion
 generate_chat_completion = chat_completion
 
 
+_tool_call_resolve_locks: dict[str, asyncio.Lock] = {}
+
+
 @app.post('/api/v1/chats/{id}/messages/{message_id}/resolve')
 async def resolve_chat_message_tool_call(
     request: Request,
@@ -1897,7 +1900,14 @@ async def resolve_chat_message_tool_call(
     user=Depends(get_verified_user),
     db: AsyncSession = Depends(get_async_session),
 ):
-    resolution = await resolve_tool_call_output(id, message_id, form_data, user, db=db)
+    redis = request.app.state.redis
+    if redis:
+        resolve_lock = redis.lock(f'{REDIS_KEY_PREFIX}:tool_call:resolve_lock:{message_id}', timeout=60)
+    else:
+        resolve_lock = _tool_call_resolve_locks.setdefault(message_id, asyncio.Lock())
+
+    async with resolve_lock:
+        resolution = await resolve_tool_call_output(id, message_id, form_data, user, db=db)
     payload = await build_tool_approval_resume_payload(id, message_id, chat=resolution['chat'])
     result = await chat_completion(request, payload, user)
     return {
diff --git a/backend/open_webui/utils/tool_approval.py b/backend/open_webui/utils/tool_approval.py
index 7d5376bb01..d59999e665 100644
--- a/backend/open_webui/utils/tool_approval.py
+++ b/backend/open_webui/utils/tool_approval.py
@@ -55,9 +55,11 @@ async def resolve_tool_call_output(
     function_call.setdefault('call_id', form_data.call_id)
     tool_name = function_call.get('name')
 
-    if any(
-        item.get('type') == 'function_call_output' and item.get('call_id') == form_data.call_id for item in output
-    ) or function_call.get('status') not in {'pending', 'queued', 'requires_approval'}:
+    if (
+        any(item.get('type') == 'function_call_output' and item.get('call_id') == form_data.call_id for item in output)
+        or function_call.get('status') not in {'pending', 'queued', 'requires_approval'}
+        or function_call.get('approved') is True
+    ):
         raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail='Tool call has already been resolved.')
 
     if form_data.action == 'approve':