#service mgmt-vmware restart
#service vmware-vpxa restart (the HA agent)
Both of these agents can be restarted without affecting VM operation. Restarting them can be a useful step in troubleshooting if vCenter has trouble connecting to a host or if you experience HA errors.
Here's link to KB article
For restarting mgmt agents in ESXi, this can be done via the console menu interface, see link above.