Minlength and maxlength not working for international mobile numbers

I have a signup page on a website. It has one field to capture mobile numbers and for that I have applied intl_tel field. The field is showing fine but it doesn’t validate the numbers range.

Here is code:

[intl_tel your-phone class:digits class:form-control minlength=6 maxlength=15 initialCountry:US preferredCountries:+1-us]

I want to accept only the numbers between 6 and 15 characters long. But currently the form accepts all mobile numbers of any length.