Thanks to JDandChips for pointing me to the solution. It works perfectly in combination with the longclick plugin. For documentation sake I’ll post my own answer to show what I did.
HTML:
<script type="text/javascript"
src="https://raw.github.com/pisi/Longclick/master/jquery.longclick-min.js"></script>
<p><a href="http://www.google.com/">Longclick me!</a></p>
The Javascript already was OK:
function longClickHandler(e){
e.preventDefault();
$("body").append("<p>You longclicked. Nice!</p>");
}
$("p a").longclick(250, longClickHandler);
The fix was to add these rules to the style sheet:
body { -webkit-touch-callout: none !important; }
a { -webkit-user-select: none !important; }