Found a working solution. I'm sharing it incase someone has encountered the same problem. Run these commands form ssh:

    sudo apt-get install pkg-config libmagickwand-dev -y
    cd /tmp
    wget http://pecl.php.net/get/imagick-3.4.0RC2.tgz
    tar xvzf imagick-3.4.0RC2.tgz
    cd imagick-3.4.0RC2
    phpize
    ./configure
    sudo make install
    rm -rf /tmp/imagick-3.4.0RC2*
    sudo chmod 666 /etc/php/7.0/fpm/php.ini
    echo extension=imagick.so >> /etc/php/7.0/fpm/php.ini
    sudo service php7.0-fpm restart
    sudo service nginx restart  

These will install imagick-3.4.0RC2 for php7. When imagick will be released I suppose that there will be an easier solution.

Cheers!

Hi, Great post, found an easier solution if anyone is in the same situation.

sudo apt-get install pkg-config libmagickwand-dev -y
sudo pecl install imagick-beta

This would install the latest beta release which is currently marked as 3.4.0RC6

Cheers :)