Create a user and set the password
You can do it by PHP rule action,
first create a function in your custom module 
as example

function _yourfuction_user_change pass($account,$pass){
    user_save($account,array('pass'=&gt;$pass));
}


Then in your rule in action section select php action and in it's field 
enter

 _yourfuction_user_change pass($account,'111111'); //your password=111111 and $account = available account parameter in field


and another solution is create your on action