If you don't want to use dangerouslySetInnerHTML then you can use the below mentioned solution
var Iframe = React.createClass({
render: function() {
return(
<div>
<iframe src={this.props.src} height={this.props.height} width={this.props.width}/>
</div>
)
}
});
ReactDOM.render(
<Iframe src="http://plnkr.co/" height="500" width="500"/>,
document.getElementById('example')
);
here live demo is available Demo