Angelo de la Cruz appeared in good health as he read the letter in a tape broadcast on Thursday.
He also thanked Philippines President Gloria Arroyo's decision to withdraw Manila's troops from the occupied country and urged her to stick to her stance.
De la Cruz's captors had theatened to behead the father of eight if Manila did not withdraw its 43 soldiers and eight policemen by 20 July, one month ahead of schedule.
De la Cruz was captured earlier this month, the lastest victim in a string of attacks targeting foreigners.
In the video he was no longer wearing the bright orange garment he had worn in previous videos. Other foreign captives killed by armed men had been wearing a similar garment in videos showing their deaths.
But the group then said in a statement aired on Aljazeera that it would release de la Cruz only after Manila's troops have all withdrawn from Iraq.
Manila asked Syria's help on Thursday in securing the release of de la Cruz, said Philippines director-general at the National Security Council Norberto B. Gonzales.
Gonzales, on a trip to Syria, discussed the matter with Syrian Foreign Minister Faruk al-Sharaa.
Arroyo was under US pressure not
to pullout early
Following their talks, Gonzales told reporters the aim of his visit was to seek Syria's assistance concerning the captive's crisis "that has befallen our country".
"We are here to ask for help," he said without explaining how could Syria assist.
Syria's official news agency said Gonzales handed al-Sharaa a message from Arroyo for Syrian President Bashar
Assad. The agency did not disclose the message's contents.
Iraqi PM's plea
In related developments, Iraq's interim prime minister Iyad Allawi urged Arroyo not to give in to the captors' demands and pull troops out of Iraq.
"I have spoken to the president of the Philippines urging her to reconsider withdrawing forces," Allawi told a news conference, referring to a telephone conversation with Arroyo.
"Our policy is no negotiation," Allawi said.
The United States has already piled pressure on its Asian
ally, a large recipient of US military and other aid, urging
it not to cave in to the armed men's demands.
The demand has left Arroyo, fresh from winning a new term in office, walking a tightrope between demands at home to save de la Cruz's life and efforts to please Washington.