Hamid Karzai's announcement unleashed a brief spell of confusion across the country.
The United Nations is trying to implement a truce and troop-withdrawal accord in Hodeidah.
Martin Griffiths hosted peace talks between the Saudi-backed Yemeni government and Iran-aligned Houthi rebels last month.
Griffiths' visit comes as the ceasefire in Hodeida was generally holding.
A pro-government official said that the loyalists were surprised by reports of a port handover.
Western powers, the United Nations and human rights groups have repeatedly pointed to chemical attacks by Assad's forces.
China has said it will import more US products to reduce its trade surplus, but no dollar amount has been publicly discussed.
Fighting erupted when Syrian troops seized a position in a rural area in the north of neighbouring Hama province that had been held by the Jaish al-Izza group.
The barrage of rockets triggered extensive retaliatory strikes by Israeli aircraft against Gaza that risked escalating into a wider conflict.
The violence came despite talk of progress towards an Egyptian-brokered deal to end protests along the border.
The civil war has killed more than 360,000 people and forced millions to flee their homes since it erupted in 2011 with the brutal repression of anti-government protests.
Gaza has seen a surge in tensions since Palestinians launched weekly border protests on March 30, drawing Israeli army fire that has killed at least 157 people.
Turkey suffered heavy losses on Thursday during its offensive against a Kurdish militia in northwest Syria, with the military announcing that eight soldiers were killed and 13 more wounded.
With IS' once-sprawling "caliphate" now wiped off the map, the regime has looked bent on completing its reconquest and Eastern Ghouta is a key target.