diff -u b/core/modules/migrate/src/Plugin/MigrateIdMapInterface.php b/core/modules/migrate/src/Plugin/MigrateIdMapInterface.php
--- b/core/modules/migrate/src/Plugin/MigrateIdMapInterface.php
+++ b/core/modules/migrate/src/Plugin/MigrateIdMapInterface.php
@@ -69,13 +69,15 @@
    * Retrieves an iterator over messages relate to source records.
    *
    * @param array $source_id_values
-   *   The source identifier values of a specific record to retrieve. If empty,
-   *   all messages are retrieved.
+   *   (optional) The source identifier values of a specific record to retrieve.
+   *   If empty, all messages are retrieved.
+   * @param int $level
+   *   (optional) Message severity. If NULL, retrieve messages of all severities.
    *
-   * @return object[]
-   *   Retrieves a list of message rows.
+   * @return \Iterator
+   *   Retrieves an iterator over the message rows.
    */
-  public function getMessageIterator(array $source_id_values = []);
+  public function getMessageIterator(array $source_id_values = [], $level = NULL);
 
   /**
    * Prepares to run a full update.
diff -u b/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php b/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php
--- b/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php
+++ b/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php
@@ -562,13 +562,16 @@
   /**
    * {@inheritdoc}
    */
-  public function getMessageIterator(array $source_id_values = []) {
+  public function getMessageIterator(array $source_id_values = [], $level = NULL) {
     $query = $this->getDatabase()->select($this->messageTableName(), 'msg')
       ->fields('msg');
     $count = 1;
     foreach ($source_id_values as $id_value) {
       $query->condition('sourceid' . $count++, $id_value);
     }
+    if ($level) {
+      $query->condition('level', $level);
+    }
     return $query->execute();
   }
 
diff -u b/core/modules/migrate/tests/src/Unit/MigrateSqlIdMapTest.php b/core/modules/migrate/tests/src/Unit/MigrateSqlIdMapTest.php
--- b/core/modules/migrate/tests/src/Unit/MigrateSqlIdMapTest.php
+++ b/core/modules/migrate/tests/src/Unit/MigrateSqlIdMapTest.php
@@ -306,6 +306,15 @@
       $this->assertEquals(MigrationInterface::MESSAGE_ERROR, $message_row->level);
     }
     $this->assertEquals($count, 1);
+
+    // Retrieve messages with a specific level.
+    $messages = $id_map->getMessageIterator([], MigrationInterface::MESSAGE_WARNING);
+    $count = 0;
+    foreach ($messages as $key => $message_row) {
+      $count = 1;
+      $this->assertEquals(MigrationInterface::MESSAGE_WARNING, $message_row->level);
+    }
+    $this->assertEquals($count, 1);
   }
 
   /**