Following talks with his Turkish counterpart Ahmet Necdet Sezer on Tuesday, al-Asad said they condemned any moves that could endanger occupied Iraq's territorial unity.
Both countries are worried that the Iraqi Kurds could capitalise on their war-time alliance with the United States to push for autonomy in their homeland in northern Iraq and set an example for their kinsmen in neighbouring Turkey and Syria.
Sezer echoed al-Asad's call to protect Iraq's unity, adding that stability should be restored in the increasingly turbulent country as soon as possible.
Al-Asad's three-day visit bears witness to improving ties between Turkey and Syria, former foes who nearly went to war in 1998 over Ankara's accusations that Damascus was backing Turkish Kurdish rebels.
"We have moved together from an atmosphere of distrust to one of trust. We now have to change the atmosphere of instability in the region to one of stability," al-Asad said, describing his visit as "historical."
The two leaders witnessed the signing of three accords aimed at preventing double taxation in bilateral trade, encouraging mutual investments and cooperation in the tourism sector.
Both Turkey and Syria host
Two-way trade between Turkey and Syria amounted to about $1 billion last year.
Bilateral ties hit an all-time low when Ankara threatened military action if Damascus continued to shelter Kurdish rebel leader Abd Allah Ocalan and his Kurdistan Workers Party (PKK), waging a separatist bloody campaign against the Turkish government.
Tension eased in October that year when Syria expelled Ocalan from his long-time safe haven and pledged to stop supporting his rebels, under a security deal it signed with Turkey.
Turkey, a close Muslim ally of the United States and a NATO member, has pushed for closer ties with Syria since the US invasion of Iraq despite warnings from Washington that its cooperation with Damascus should be limited.
Washington accuses Damascus of supporting "terrorism" and developing weapons of mass destruction, allegations Syria categorically denies.
In related news, al-Asad issued fresh calls for a Middle East free of weapons of mass destruction, but defended his right to acquire them against Israeli aggression.
Speaking to reporters, the Syrian leader said Ankara had backed his appeals. Turkey declined to comment on his remarks.
Syria is also technically at war with Israel, Turkey's main ally in the region.
Ankara has offered on several occasions to mediate or to "facilitate" contacts between the parties in the Middle East conflict.
Al-Asad recently offered to resume peace negotiations with Israel, four years after they broke down.
But despite this rapprochement, Turkey and Syria remain at odds over the sharing of the waters of the Euphrates - which originates in Turkey - and Syrian claims to Turkey's southeastern province of Hatay.