How to update drupal (with composer) and not update to the latest major drupal release not very familiar with composer yet 

I run composer update on a dev version (thank GOD) but from 8.2.6 drupal was updated to 8.3.0 but some functionality was broken due to the upgrade ... how can I safely run composer update and not upgrade to latest drupal ... or is there some other command I should run instead ?

I understand that I probably have to change the composer.json to do it but I don't quite know what it is that it I need to include in it 

Any help would be appeciated 

this doc article don't quite explain such a thing

UPDATE

I run the command from eyal composer require drupal/drupal:8.2.* but creates problem and site was unusable after that (received 500 error)

giorgos@glaptop:~/websites/domain.com$ composer require drupal/drupal:8.2.*
./composer.json has been updated
No patches supplied.
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 1 install, 0 updates, 0 removals
No patches supplied.
Gathering patches for dependencies. This might take a minute.
  - Installing drupal/drupal (dev-8.2.x 2125663)  Cloning 2125663da0 from cache
Writing lock file
Generating autoload files

Installation failed, reverting ./composer.json to its original content.


  [RuntimeException]                                                                                               
  Could not scan for classes inside "docroot/core/lib/Drupal.php" which does not appear to be a file nor a folder  


require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [&lt;packages&gt;]...


I had to run composer update and now with the 8.3.1 version of drupal the composer update run smoothly.  I just needed to run drush up rules-8.x-3.x-dev after that since there was a problem with rules and 8.3.1 

EDIT
Anyone knows why my question received -2 ? (was I downvoted ? what is the reason ?)
It depends on the version you specify in the composer.json file. You can specify broad versioning, or exact version, and composer will adhere to that.