Hi Prathik,
Set your shell property setAppWidthLimited(true).
This following code dump might help you
var Shell = new sap.m.Shell("Shell",{})
var app = new sap.m.App("app",{initialPage:"idtest1"});
var page = sap.ui.view({id:"idtest1", viewName:"shell.test", type ap.ui.core.mvc.ViewType.JS});
Shell.setApp(app);
Shell.setAppWidthLimited(true);
app.addPage(page);
Shell.placeAt("content");
Regards,
Vijay.