Israeli tanks and armoured vehicles made a brief raid into the territory overnight after an area near the Israeli settlement of Netzarim was targeted by mortar fire.
The column closed in on a building from where the shots were apparently fired, but then withdrew.
Earlier four Hamas followers escaped unharmed when a drone fired two rockets on a car near the southern Gaza town of Khan Yunis.
“The Israeli air force targeted a mortar shell launcher and a vehicle carrying additional mortar shells, including a launcher that was used to fire at Israeli targets,” an Israeli military spokesman said.
Hamas said it later fired three rockets at Jewish settlements in southern Gaza in “answer to the Israeli targeting of the group”.
The incursion came a day after two Palestinians and a Chinese labourer were killed in a Palestinian militant attack on a Jewish settlement in southern Gaza, claimed by Hamas and Islamic Jihad.
The Palestinian leader appealed for calm from all sides, while also condemning the Israeli strike.
“This raid cannot be justified as it sabotages the calm,” he said on his arrival in Gaza to meet Hamas and other factions.
Mr Abbas and Israeli Prime Minister Ariel Sharon, who are set to
meet on June 21, declared an end to hostilities at a summit in February.
The recent spike in violence has prompted calls from within the Israeli government to postpone the planned pullout from Gaza due to start in mid-August.
But Mr Sharon insisted there were no grounds for delay.
“There are those who hope that the disengagement will not be carried out. I want to say unequivocally that it will be carried out on schedule,” he said.
Meanwhile, visiting British Foreign Secretary Straw said the UK would do “everything” in its power to make the Gaza pullout successful.
Mr Abbas’s talks in Gaza were also expected to cover his decision to delay the first Palestinian parliamentary elections in nine years, a move that has angered Hamas.
Hamas hoped a strong showing in the ballot would secure its entry into the political mainstream, but Mr Straw said electoral success for Hamas would not see it removed from a terror blacklist.