enq: TX - row lock contention creating session waits The database I'm working on has session waits due to DMLs on numerous tables in a procedure. 

The DBA identifies this as enq: TX - row lock contention.

How can I resolve this issue?
You are holding locks due to an UPDATE statemnt. Those locks are released when you commit your transaction. 

To solve this issue, make sure you commit your transactions as soon as possible.