@ushadatt, This is the due to the output of the date filter.
The solution is to not use the date filter at all. Simply index your date string as a regular field, and Elasticsearch can recognize it. I say 'can' because in your case, the date string will not parse because of the space between the date and time (by default). To work around that, you can either change your date format, or you can specify the mapping as a custom date format in Elasticsearch by updated the properties section of the logstash template like so:
"format": "yyyy-MM-dd HH:mm:ss"
Here is the Elastic reference on the Date Format mapping: