diff --git a/packages/block-library/src/embed/transforms.js b/packages/block-library/src/embed/transforms.js
index e1b2f256e2d56d..37c92fc3d1c264 100644
--- a/packages/block-library/src/embed/transforms.js
+++ b/packages/block-library/src/embed/transforms.js
@@ -2,6 +2,7 @@
  * WordPress dependencies
  */
 import { createBlock } from '@wordpress/blocks';
+import { isURL, getFilename } from '@wordpress/url';
 
 /**
  * Internal dependencies
@@ -22,10 +23,24 @@ const transforms = {
 	from: [
 		{
 			type: 'raw',
-			isMatch: ( node ) =>
-				node.nodeName === 'P' &&
-				/^\s*(https?:\/\/\S+)\s*$/i.test( node.textContent ) &&
-				node.textContent?.match( /https/gi )?.length === 1,
+			isMatch: ( node ) => {
+				if ( node.nodeName !== 'P' ) {
+					return false;
+				}
+				const trimmed = node.textContent.trim();
+				if (
+					! isURL( trimmed ) ||
+					! /^https:\/\//i.test( trimmed ) ||
+					trimmed.match( /https:\/\//gi )?.length !== 1
+				) {
+					return false;
+				}
+				// Reject URLs whose filename ends in a file extension,
+				// except common page extensions used by permalinks.
+				return ! /\.(?!(html?|php)$)[a-z0-9]+$/i.test(
+					getFilename( trimmed ) || ''
+				);
+			},
 			transform: ( node ) => {
 				const url = rewriteXToTwitter( node.textContent.trim() );
 				return createBlock( EMBED_BLOCK, {