You would need to rebuild the widget from here, on line 156 the properties are set. If you add the property 'draggable:false' it should prevent the map from being moved. Full google maps api can be found here.
Does this help?
http://stackoverflow.com/questions/21992498/disable-mouse-scroll-wheel-zoom-on-embedded-google-maps
The mentioned Google Maps widget is not supported, the new one is this one and is supported. If this is an issue, please file a feature request on Github. I can check if this needs to be implemented. If it's something in the Google Maps API, i can add an option in the modeler for this widget