diff --git a/integrations/google_vertex/src/haystack_integrations/components/generators/google_vertex/chat/gemini.py b/integrations/google_vertex/src/haystack_integrations/components/generators/google_vertex/chat/gemini.py
index c94367b41..2309ca718 100644
--- a/integrations/google_vertex/src/haystack_integrations/components/generators/google_vertex/chat/gemini.py
+++ b/integrations/google_vertex/src/haystack_integrations/components/generators/google_vertex/chat/gemini.py
@@ -1,3 +1,4 @@
+import json
 import logging
 from typing import Any, Callable, Dict, Iterable, List, Optional, Union
 
@@ -41,7 +42,7 @@ class VertexAIGeminiChatGenerator:
     messages = [ChatMessage.from_user("Tell me the name of a movie")]
     res = gemini_chat.run(messages)
 
-    print(res["replies"][0].content)
+    print(res["replies"][0].text)
     >>> The Shawshank Redemption
     ```
     """
@@ -209,31 +210,31 @@ def _convert_part(self, part: Union[str, ByteStream, Part]) -> Part:
     def _message_to_part(self, message: ChatMessage) -> Part:
         if message.role == ChatRole.ASSISTANT and message.name:
             p = Part.from_dict({"function_call": {"name": message.name, "args": {}}})
-            for k, v in message.content.items():
+            for k, v in json.loads(message.text).items():
                 p.function_call.args[k] = v
             return p
-        elif message.role in {ChatRole.SYSTEM, ChatRole.ASSISTANT}:
-            return Part.from_text(message.content)
-        elif message.role == ChatRole.FUNCTION:
-            return Part.from_function_response(name=message.name, response=message.content)
-        elif message.role == ChatRole.USER:
-            return self._convert_part(message.content)
+        elif message.is_from(ChatRole.SYSTEM) or message.is_from(ChatRole.ASSISTANT):
+            return Part.from_text(message.text)
+        elif message.is_from(ChatRole.FUNCTION):
+            return Part.from_function_response(name=message.name, response=message.text)
+        elif message.is_from(ChatRole.USER):
+            return self._convert_part(message.text)
 
     def _message_to_content(self, message: ChatMessage) -> Content:
-        if message.role == ChatRole.ASSISTANT and message.name:
+        if message.is_from(ChatRole.ASSISTANT) and message.name:
             part = Part.from_dict({"function_call": {"name": message.name, "args": {}}})
-            for k, v in message.content.items():
+            for k, v in json.loads(message.text).items():
                 part.function_call.args[k] = v
-        elif message.role in {ChatRole.SYSTEM, ChatRole.ASSISTANT}:
-            part = Part.from_text(message.content)
-        elif message.role == ChatRole.FUNCTION:
-            part = Part.from_function_response(name=message.name, response=message.content)
-        elif message.role == ChatRole.USER:
-            part = self._convert_part(message.content)
+        elif message.is_from(ChatRole.SYSTEM) or message.is_from(ChatRole.ASSISTANT):
+            part = Part.from_text(message.text)
+        elif message.is_from(ChatRole.FUNCTION):
+            part = Part.from_function_response(name=message.name, response=message.text)
+        elif message.is_from(ChatRole.USER):
+            part = self._convert_part(message.text)
         else:
             msg = f"Unsupported message role {message.role}"
             raise ValueError(msg)
-        role = "user" if message.role in [ChatRole.USER, ChatRole.FUNCTION] else "model"
+        role = "user" if message.is_from(ChatRole.USER) or message.is_from(ChatRole.FUNCTION) else "model"
         return Content(parts=[part], role=role)
 
     @component.output_types(replies=List[ChatMessage])
@@ -283,7 +284,7 @@ def _get_response(self, response_body: GenerationResponse) -> List[ChatMessage]:
                 elif part.function_call:
                     metadata["function_call"] = part.function_call
                     new_message = ChatMessage.from_assistant(
-                        content=dict(part.function_call.args.items()), meta=metadata
+                        content=json.dumps(dict(part.function_call.args)), meta=metadata
                     )
                     new_message.name = part.function_call.name
                     replies.append(new_message)
@@ -311,7 +312,7 @@ def _get_stream_response(
                         replies.append(ChatMessage.from_assistant(content, meta=metadata))
                     elif part.function_call:
                         metadata["function_call"] = part.function_call
-                        content = dict(part.function_call.args.items())
+                        content = json.dumps(dict(part.function_call.args))
                         new_message = ChatMessage.from_assistant(content, meta=metadata)
                         new_message.name = part.function_call.name
                         replies.append(new_message)