var app = angular.module('http',[],function($interpolateProvider) {
    $interpolateProvider.startSymbol('<%');
    $interpolateProvider.endSymbol('%>');
});

app.directive('numbersOnly', function(){
   return {
     require: 'ngModel',
     link: function(scope, element, attrs, modelCtrl) {
       modelCtrl.$parsers.push(function (inputValue) {
           if (inputValue == undefined) return '' 
           var transformedInput = inputValue.replace(/[^0-9]/g, ''); 
           if (transformedInput!=inputValue) {
              modelCtrl.$setViewValue(transformedInput);
              modelCtrl.$render();
           }         

           return transformedInput;         
       });
     }
   };
});
     

<input type="text" numbers-only="numbers-only">