There is no way to validate what to is to be pasted. But after pasting you can clean the content as show in the below code
<script type="text/javascript">
function clean(t) {
t.value = t.value.toString().replace(/[^a-zA-Z 0-9\n\r]+/g, '');
}
</script>
<input type="text" id="text1" onchange = "clean(this)" />