diff --git a/test/framework/src/main/java/org/opensearch/test/rest/yaml/ClientYamlTestClient.java b/test/framework/src/main/java/org/opensearch/test/rest/yaml/ClientYamlTestClient.java
index 13ede9d44f1ad..849d7e4685a76 100644
--- a/test/framework/src/main/java/org/opensearch/test/rest/yaml/ClientYamlTestClient.java
+++ b/test/framework/src/main/java/org/opensearch/test/rest/yaml/ClientYamlTestClient.java
@@ -59,6 +59,8 @@
 import java.io.UncheckedIOException;
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.net.URLEncoder;
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
@@ -193,7 +195,7 @@ public ClientYamlTestResponse callApi(
             String contentType = entity.getContentType();
             // randomly test the GET with source param instead of GET/POST with body
             try {
-                if (sendBodyAsSourceParam(supportedMethods, contentType, entity.getContentLength())) {
+                if (sendBodyAsSourceParam(supportedMethods, contentType, entity)) {
                     logger.debug("sending the request body as source param with GET method");
                     queryStringParams.put("source", EntityUtils.toString(entity));
                     queryStringParams.put("source_content_type", contentType);
@@ -253,11 +255,13 @@ protected static void setOptions(Request request, Map<String, String> headers) {
         request.setOptions(options);
     }
 
-    private static boolean sendBodyAsSourceParam(List<String> supportedMethods, String contentType, long contentLength) {
+    private static boolean sendBodyAsSourceParam(List<String> supportedMethods, String contentType, HttpEntity entity) throws IOException,
+        ParseException {
         if (false == supportedMethods.contains(HttpGet.METHOD_NAME)) {
             // The API doesn't claim to support GET anyway
             return false;
         }
+        long contentLength = entity.getContentLength();
         if (contentLength < 0) {
             // Negative length means "unknown" or "huge" in this case. Either way we can't send it as a parameter
             return false;
@@ -271,7 +275,18 @@ private static boolean sendBodyAsSourceParam(List<String> supportedMethods, Stri
             // We can only encode JSON or YAML this way.
             return false;
         }
-        return RandomizedTest.rarely();
+
+        return RandomizedTest.rarely() && isUrlEncodedLengthUnderLimit(entity);
+    }
+
+    /*
+     * There is a limit of 4096 bytes for the HTTP line, otherwise there will be too_long_http_line_exception.
+     * We check if the length of the url-encoded source parameter is less than 3000, leaving remaining for
+     * url and other params.
+     */
+    private static boolean isUrlEncodedLengthUnderLimit(HttpEntity entity) throws IOException, ParseException {
+        String encoded = URLEncoder.encode(EntityUtils.toString(entity), StandardCharsets.UTF_8);
+        return encoded.length() < 3000;
     }
 
     private ClientYamlSuiteRestApi restApi(String apiName) {