time.Date(t.Year(), t.Month(), time.Now().Day(), 10, 0, 0, 0, time.UTC)
I want to set dateTime of 10:00:00 AM in IST format in golang.
It depends on the format of the time you have at hand. Go has some standard time formats ready as consts in the time package, but you can specify your own standard if it's custom. Regarding the time zone, you can parse or output a time in a specific time zone. Here is an example of parsing a time string in IST, and outputting it as UTC. It's not clear from your question what is your precise problem but I hope this helps:
// First, we create an instance of a timezone location object
loc, _ := time.LoadLocation("Asia/Kolkata")
// this is our custom format. Note that the format must point to this exact time
format := "Jan _2 2006 3:04:05 PM"
// this is your timestamp
timestamp := "Jun 25 2015 10:00:00 AM"
// now we parse it, considering it's in IST
t, err := time.ParseInLocation(format, timestamp, loc)
// printing it prints it in IST, but you can set the timezone to UTC if you want
fmt.Println(t, err)
// example - getting the UTC timestamp
fmt.Println(t.UTC())