Query for Tweet within time interval using tweepy

I am trying to use tweepy to query for tweet that falls within certain interval.

Using the snippet below for days interval works:

page_count = 0
for tweets in tweepy.Cursor(api.search,q=query,count=100,result_type="recent",include_entities=True,since= "2016-02-18", until= "2016-03-18" ).pages():
    page_count+=1
    print tweets[0].text.encode('utf-8')
    if page_count >=20:
        break

but i want it to be within time interval e.g (between 06:00 and 13:00). I tried using this query but it returns nothing:

for tweets in tweepy.Cursor(api.search,q=query,count=100,result_type="recent",include_entities=True,since= "2016-03-18 05:30", until= "2016-03-18 08:30" ).pages():
    page_count+=1
    print tweets[0].text.encode('utf-8')
    if page_count >=20:
        break

How do i do this. Thanks