diff --git a/tests/tool_use/test_mistral_tool_parser.py b/tests/tool_use/test_mistral_tool_parser.py
index e5deb7f40eb35..2dd0399cb8eeb 100644
--- a/tests/tool_use/test_mistral_tool_parser.py
+++ b/tests/tool_use/test_mistral_tool_parser.py
@@ -615,6 +615,7 @@ def test_extract_tool_calls_streaming(
         "single_tool_weather",
         "multiple_tool_calls",
         "content_before_tool",
+        "complex",
     ],
     argnames=["model_output", "expected_tool_calls", "expected_content"],
     argvalues=[
@@ -673,6 +674,21 @@ def test_extract_tool_calls_streaming(
             ],
             "bla",
         ),
+        (
+            # Complex
+            """[TOOL_CALLS]bash{"command": "print(\\"hello world!\\")\\nre.compile(r\'{}\')"}""",  # noqa: E501
+            [
+                ToolCall(
+                    function=FunctionCall(
+                        name="bash",
+                        arguments=json.dumps(
+                            {"command": "print(\"hello world!\")\nre.compile(r'{}')"}
+                        ),
+                    )
+                )
+            ],
+            "",
+        ),
     ],
 )
 def test_extract_tool_calls_streaming_one_chunk(
diff --git a/vllm/entrypoints/openai/tool_parsers/mistral_tool_parser.py b/vllm/entrypoints/openai/tool_parsers/mistral_tool_parser.py
index aa5089ffe84d7..bc827f045606c 100644
--- a/vllm/entrypoints/openai/tool_parsers/mistral_tool_parser.py
+++ b/vllm/entrypoints/openai/tool_parsers/mistral_tool_parser.py
@@ -99,12 +99,7 @@ class MistralToolParser(ToolParser):
         self.bot_token = "[TOOL_CALLS]"
         self.bot_token_id = self.vocab.get(self.bot_token)
         self.tool_call_regex = re.compile(r"\[{.*}\]", re.DOTALL)
-        if not _is_pre_v11_tokeniser(self.model_tokenizer):
-            self.fn_name_regex = re.compile(
-                r"([a-zA-Z0-9_-]+)(\{[\s\S]*?\}+)", re.DOTALL
-            )
-        else:
-            self.fn_name_regex = None
+        self._is_pre_v11 = _is_pre_v11_tokeniser(self.model_tokenizer)
 
         if self.bot_token_id is None:
             raise RuntimeError(
@@ -148,23 +143,24 @@ class MistralToolParser(ToolParser):
         tool_content = model_output.replace(self.bot_token, "").strip()
 
         try:
-            # we first try to directly load the json as parsing very nested
-            # jsons is difficult
             try:
-                if self.fn_name_regex:
+                if not self._is_pre_v11:
                     function_call_arr = []
                     for single_tool_content in model_output.split(self.bot_token):
-                        matches = self.fn_name_regex.findall(single_tool_content)
+                        if "{" not in single_tool_content:
+                            continue
 
-                        for match in matches:
-                            fn_name = match[0]
-                            args = match[1]
+                        end_name = single_tool_content.find("{")
+                        fn_name, args = (
+                            single_tool_content[:end_name],
+                            single_tool_content[end_name:],
+                        )
 
-                            # fn_name is encoded outside serialized json dump
-                            # only arguments are serialized
-                            function_call_arr.append(
-                                {"name": fn_name, "arguments": json.loads(args)}
-                            )
+                        # fn_name is encoded outside serialized json dump
+                        # only arguments are serialized
+                        function_call_arr.append(
+                            {"name": fn_name, "arguments": json.loads(args)}
+                        )
                 else:
                     function_call_arr = json.loads(tool_content)
             except json.JSONDecodeError: