You can use AWAF only with SSL offloaded as the F5 AWAF inbuilt with LTM functionality which is necessary for HTTP applications.check the below link for LTM features available within AWAF license
https://my.f5.com/manage/s/article/K14231234
If you have any policy to use LTM at edge with ssl offload and AWAF with Plain HTTP traffic and keep the Public IP visibility in WAF and server then you have to rely on the XFF (X-Forwarded-For) header value.
[LTM inserts the Client IP in X-Forwarded-For header and in AWAF http profile with accept XFF, and waf policy with Trust XFF should be enabled)
But XFF value can be Spoofed and AWAF will not be much effective to block if multiple ip address are present in XFF header and also L7 DOS will not be effective.
as suggested by Mohamed_Ahmed_Kansoh's better use AWAF at edge(so AWAF take action on L3 IPaddress value) and LTM to load balance your servers. Either you can use Full SSL ie SSL in AWAF and SSL offload in LTM. or SSL only in AWAF and plain HTTP in LTM and backend servers
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one more advantage of using AWAF at edge , as you can use the Priority Group option to failover, to direct servers in case LTM fails or down. A pool With both LTM VIP and Backend server IPs a members, LTM VIP member with higher priority and priority group value less than 1. If LTM VIP /device is down the traffic will be load balanced to backend servers along with waf capability.