diff --git a/esphome/components/api/api_pb2_dump.cpp b/esphome/components/api/api_pb2_dump.cpp
index bf4ca5e402..e5120007ae 100644
--- a/esphome/components/api/api_pb2_dump.cpp
+++ b/esphome/components/api/api_pb2_dump.cpp
@@ -3485,7 +3485,11 @@ void VoiceAssistantAudio::dump_to(std::string &out) const {
   __attribute__((unused)) char buffer[64];
   out.append("VoiceAssistantAudio {\n");
   out.append("  data: ");
-  out.append(format_hex_pretty(this->data_ptr_, this->data_len_));
+  if (this->data_ptr_ != nullptr) {
+    out.append(format_hex_pretty(this->data_ptr_, this->data_len_));
+  } else {
+    out.append(format_hex_pretty(reinterpret_cast<const uint8_t *>(this->data.data()), this->data.size()));
+  }
   out.append("\n");
 
   out.append("  end: ");
diff --git a/script/api_protobuf/api_protobuf.py b/script/api_protobuf/api_protobuf.py
index 298f0a6d18..0cfa7fc344 100755
--- a/script/api_protobuf/api_protobuf.py
+++ b/script/api_protobuf/api_protobuf.py
@@ -657,12 +657,23 @@ class BytesType(TypeInfo):
         return f"buffer.encode_bytes({self.number}, this->{self.field_name}_ptr_, this->{self.field_name}_len_);"
 
     def dump(self, name: str) -> str:
-        # Use pointer/length if available (SOURCE_SERVER/SOURCE_BOTH), otherwise use std::string
-        if self.needs_encode:
-            return f"out.append(format_hex_pretty(this->{self.field_name}_ptr_, this->{self.field_name}_len_));"
-        else:
+        # For SOURCE_CLIENT only, always use std::string
+        if not self.needs_encode:
             return f"out.append(format_hex_pretty(reinterpret_cast<const uint8_t*>(this->{self.field_name}.data()), this->{self.field_name}.size()));"
 
+        # For SOURCE_SERVER, always use pointer/length
+        if not self.needs_decode:
+            return f"out.append(format_hex_pretty(this->{self.field_name}_ptr_, this->{self.field_name}_len_));"
+
+        # For SOURCE_BOTH, check if pointer is set (sending) or use string (received)
+        return (
+            f"if (this->{self.field_name}_ptr_ != nullptr) {{\n"
+            f"    out.append(format_hex_pretty(this->{self.field_name}_ptr_, this->{self.field_name}_len_));\n"
+            f"  }} else {{\n"
+            f"    out.append(format_hex_pretty(reinterpret_cast<const uint8_t*>(this->{self.field_name}.data()), this->{self.field_name}.size()));\n"
+            f"  }}"
+        )
+
     def get_size_calculation(self, name: str, force: bool = False) -> str:
         return f"ProtoSize::add_bytes_field(total_size, {self.calculate_field_id_size()}, this->{self.field_name}_len_);"