Disable scroll wheel zoom on Google Maps iframes.

disable-zoom-gmaps.css

.google-maps-responsive {
        position: relative;
        padding-bottom: 75%; // This is the aspect ratio
        height: 0;
        overflow: hidden;
}
.google-maps-responsive iframe {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
}

disable-zoom-gmaps.js

/*

  Thanks to http://stackoverflow.com/a/25904582/165407
*/

jQuery(document).ready(function($){

	// Disable scroll zooming and bind back the click event
	var onMapMouseleaveHandler = function (event) {
	  var that = $(this);

	  that.on('click', onMapClickHandler);
	  that.off('mouseleave', onMapMouseleaveHandler);
	  that.find('iframe').css("pointer-events", "none");
	}

	var onMapClickHandler = function (event) {
	  var that = $(this);

	  // Disable the click handler until the user leaves the map area
	  that.off('click', onMapClickHandler);

	  // Enable scrolling zoom
	  that.find('iframe').css("pointer-events", "auto");

	  // Handle the mouse leave event
	  that.on('mouseleave', onMapMouseleaveHandler);
	}

	// Enable map zooming with mouse scroll when the user clicks the map
	$('.google-maps-responsive').on('click', onMapClickHandler);
});