diff --git a/packages/blocks/src/store/reducer.js b/packages/blocks/src/store/reducer.js
index 4aa0b922e090fd..7c7fb4763a1cb6 100644
--- a/packages/blocks/src/store/reducer.js
+++ b/packages/blocks/src/store/reducer.js
@@ -393,6 +393,13 @@ function getMergedUsesContext( existingUsesContext = [], newUsesContext = [] ) {
 export function blockBindingsSources( state = {}, action ) {
 	switch ( action.type ) {
 		case 'ADD_BLOCK_BINDINGS_SOURCE':
+			// Only open this API in Gutenberg and for `core/post-meta` for the moment.
+			let getFieldsList;
+			if ( globalThis.IS_GUTENBERG_PLUGIN ) {
+				getFieldsList = action.getFieldsList;
+			} else if ( action.name === 'core/post-meta' ) {
+				getFieldsList = action.getFieldsList;
+			}
 			return {
 				...state,
 				[ action.name ]: {
@@ -407,7 +414,7 @@ export function blockBindingsSources( state = {}, action ) {
 					// Only set `canUserEditValue` if `setValues` is also defined.
 					canUserEditValue:
 						action.setValues && action.canUserEditValue,
-					getFieldsList: action.getFieldsList,
+					getFieldsList,
 				},
 			};
 		case 'ADD_BOOTSTRAPPED_BLOCK_BINDINGS_SOURCE':