The Enterprise Manager (EM) or WebView jetty web servers use whatever ciphersuites are enabled in Java and out of the box DES & Triple DES (3DES) ciphers are not disabled.
To disable the ciphers, edit the java.security file for the EM JRE (EM_HOME/jre/lib/java.security) and disable the relevant algorithms e.g with Java 1.8 the default value of property jdk.tls.disabledAlgorithms only includes SSLv3 so to also disable DES & 3DES change the property to:
jdk.tls.disabledAlgorithms=SSLv3, DES, DESede