Add next and previous post links on pages like category, tags or archive pages

Two problems I can see off hand here

Firstly, you should move your query to outside your if conditional statement.

Secondly, when using WP_Query, the $max_pages parameter should be used when using next_posts_link( $label , $max_pages );

So, your code should look something like this

<div class="wrapper inner_content_wrap">

  <?php next_posts_link( '<span class="label iconfont"><img src="'.get_template_directory_uri().'/images/pager_arw.png" alt=""></span><span class="entry-info-wrap">Next Entries</span>', $loop->max_num_pages); ?>
  <?php previous_posts_link( '<span class="label iconfont"><img src="'.get_template_directory_uri().'/images/pager_arw2.png" alt=""></span><span class="entry-info-wrap">previous Entries</span>'); ?>

        <div class="blog_area">
            <div class="container">


<?php   
$paged = ( get_query_var( 'paged' ) ) ? get_query_var( 'paged' ) : 1;

$args = array( 
    'post_type' => 'post', 
    'posts_per_page' => 3, 
    'paged' => $paged 
);

$loop = new WP_Query( $args );  

if($loop->have_posts()) :

    $i = '1';

    while ( $loop->have_posts() ) : $loop->the_post();  ?>

<-----REST OF YOUR CODE------->