Non sono sicuro che il file fonte.php sia corretto, vedi un pò:

fonte.php
Codice PHP:
<html>
<head>
    <title></title>
</head>
<body>
    [url='altro']altro link inutile[/url]
    <div class='gallery' id='123456'>
        <a href='lnk1' title='tlnk1'>
            <div class="classe1">
                <div class="classe2">
                    [img]img1[/img]
                </div>
                <span>
                    <div class='icona_numero_di_foto'></div>1
                </span>
            </div>
        </a>
    </div>

    <div class='gallery' id='123457'>
        <a href='lnk2' title='tlnk2'>
            <div class="classe1">
                <div class="classe2">
                    [img]img2[/img]
                </div>
                <span>
                    <div class='icona_numero_di_foto'></div>2
                </span>
            </div>
        </a>
    </div>

    <div class='gallery' id='123458'>
        <a href='lnk3' title='tlnk3'>
            <div class="classe1">
                <div class="classe2">
                    [img]img3[/img]
                </div>
                <span>
                    <div class='icona_numero_di_foto'></div>3
                </span>
            </div>
        </a>
    </div>
    [url='altro']altro link inutile 2[/url]

</body>
</html> 
index.php
codice:
<html>
<head>
	<script src='http://code.jquery.com/jquery-1.9.1.js'></script>
	<script>
		$(function(){
			$.ajax({
				url:'fonte.php',
				dataType: 'html'
			}).done(function(contenuto){
				$(contenuto).each(function(i, el){
					if($(el).hasClass('gallery')){
						var lnk = $(el).find("a:first-child");
						console.log($(lnk).attr('href'));
						var img = $(lnk).find('img.classe3');
						console.log($(img).attr('src'));
						console.log($(img).attr('title'));
						var oth = $(lnk).find("div.icona_numero_di_foto");
						console.log($.trim($(oth).parent().contents(":not(div)").text()));
					}
				});
			});
		});
	</script>
	<title></title>
</head>
<body>
</body>
</html>