Shaikh Saud bin Ibrahim al-Shraim, preacher at the Grand Mosque in Makka, told worshippers attending his Friday sermon that Saudi authorities were sincere in forgiving armed dissidents who voluntarily surrender.
"Hurry, you who have committed mistakes and are now in hiding, to make this initiative a new beginning in correcting (your behaviour) and return to the true path," Shraim said in a speech that praised repentance as an Islamic ideal.
"Hurry to catch up with those who have been promised forgiveness in life and death, for God Almighty has said to those who have repented ... that He is forgiving and merciful."
The one-month amnesty offer was announced on 23 June.
No armed dissidents have surrendered since two handed themselves in shortly after the amnesty was announced. De facto Saudi ruler Crown Prince Abd Allah issued the amnesty after the killing of the group's head Abd al-Aziz al-Muqrin.
Only one of the two men who surrenderd was on a list of 26 most-wanted people, issued last year after an anti-Western campaign claimed 85 lives.
The second is wanted for arms smuggling.
At least 13 people on the list are still at large, and experts say scores more - who are not on the list - remain free.
In a statement posted on the internet, al-Qaida supporters dismissed the amnesty. It said last month's killing of al-Muqrin would only increase the group's determination to topple the pro-US royal family ruling the regional oil power.
Saudi experts say the amnesty does not guarantee a full pardon. Under Saudi's Islamic Sharia law, victims' families are entitled to compensation and can demand the death penalty even if the state has issued a pardon.