my cluster doesnt have Ranger enabled due to which I am not able to restrict any user access. Is there any other mechanism to restrict users and provide them read only access.
Your question isn't detailed. What sort of access are you thinking of to restrict as read-only data or UI? For Ambari you have the Cluster User role which is a read-only for its services, including configurations, service status, and health alerts.
Then the other is about reading data in HDFS where you can use HDFS ACL's which is POSIX compliant like rwx but that won't work for Hive tables.
You should know that Ranger controls authorization for the following HDFS,Hive,HBase,Kafka,Knox,YARN,Storm,Atlas and other components depending oon the software HDP,CDH or CDP.