diff --git a/packages/pack/src/actions/main.ts b/packages/pack/src/actions/main.ts
index 1ec3323..4c2a951 100644
--- a/packages/pack/src/actions/main.ts
+++ b/packages/pack/src/actions/main.ts
@@ -89,7 +89,7 @@ module.exports = async function action(specifiedEntries: string[], options: any
                 }
             })
         }
-        if (eachOptions.bundle && options.forceIifeBundle) {
+        if (eachOptions.format === 'iife' && eachOptions.bundle && options.forceIifeBundle) {
             external = []
         }
         const eachOutdir = eachOptions.outdir || options.outdir