You won't be able to avoid this.
There are ways you can setup encrypted tunnels over the Internet, but both endpoint systems (or gateways between those systems) must support the encryption used. The catch is that the end hosts eventually need to see the clear text data, so whatever gets encrypted must get decrypted by the time it gets to the other end.
If you have two different nodes connected via the Internet, you can encrypt traffic between them using something like IPSec or SSL, because you can control what runs on these systems and how they communicate. If you are talking to somebody else's systems over the Internet however, you can only communicate using encryption if the system you are talking to supports that type of encryption.
Common examples of encryption being supported on Internet systems usually involve SSL, e.g. "secure" https websites, "secure" SSL protected POP3 and SMTP, etc.
Any tor traffic that gets encrypted will get decrypted when it leaves the tor exit node, at which point that exit node can sniff all of your traffic in clear text. I wouldn't send anything confidential over tor for this reason, because anyone can run a tor exit node. Your traffic being grabbed via a malicious tor exit node is actually far more likely than someone tapping your line, because tapping your line requires physical access that line and the reward probably won't justify the effort for many attackers unless you have really interesting traffic.