diff --git a/dist/index.js b/dist/index.js
index c7f2bcad1..2cca766b7 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -5825,6 +5825,12 @@ function getSource(settings) {
             // Downloading using REST API
             core.info(`The repository will be downloaded using the GitHub REST API`);
             core.info(`To create a local Git repository instead, add Git ${gitCommandManager.MinimumGitVersion} or higher to the PATH`);
+            if (settings.submodules) {
+                throw new Error(`Input 'submodules' not supported when falling back to download using the GitHub REST API`);
+            }
+            else if (settings.sshKey) {
+                throw new Error(`Input 'ssh-key' not supported when falling back to download using the GitHub REST API`);
+            }
             yield githubApiHelper.downloadRepository(settings.authToken, settings.repositoryOwner, settings.repositoryName, settings.ref, settings.commit, settings.repositoryPath);
             return;
         }
diff --git a/src/git-source-provider.ts b/src/git-source-provider.ts
index 7ce9fb793..9c08204e4 100644
--- a/src/git-source-provider.ts
+++ b/src/git-source-provider.ts
@@ -57,6 +57,16 @@ export async function getSource(settings: IGitSourceSettings): Promise<void> {
     core.info(
       `To create a local Git repository instead, add Git ${gitCommandManager.MinimumGitVersion} or higher to the PATH`
     )
+    if (settings.submodules) {
+      throw new Error(
+        `Input 'submodules' not supported when falling back to download using the GitHub REST API`
+      )
+    } else if (settings.sshKey) {
+      throw new Error(
+        `Input 'ssh-key' not supported when falling back to download using the GitHub REST API`
+      )
+    }
+
     await githubApiHelper.downloadRepository(
       settings.authToken,
       settings.repositoryOwner,