Se o Tomcat for executado nas portas padrão (8080 - HTTP, 8009 - AJP) adicione isso à sua configuração do Apache:
<VirtualHost _default_:443>
.......
ProxyRequests Off
ProxyPreserveHost On
ProxyVia On
<Proxy *>
Order deny,allow
Allow from all
</Proxy>
<Location /app>
ProxyPass ajp://localhost:8009/app
ProxyPassReverse ajp://localhost:8009/app
</Location>
#<Location /app>
# ProxyPass http://localhost:8080/app
# ProxyPassReverse http://localhost:8080/app
#</Location>
<Location "/app/WEB-INF/">
deny from all
</Location>
..........
</VirtualHost>
<VirtualHost *:80>
...........
RewriteEngine On
RewriteRule ^/app$ https://%{HTTP_HOST}%{REQUEST_URI} [R]
...........
</VirtualHost>