My Self |
rules wrote:
In melee combat, you can help a friend attack or defend by distracting or interfering with an opponent. If you're in position to make a melee attack on an opponent that is engaging a friend in melee combat, you can attempt to aid your friend as a standard action.
It probably doesn't provoke. The rules aren't so clear, but you're not actually attacking so much as distracting or interfering.