"The Israeli charge is false and not based on any evidence," Shara said at a joint news conference in Cairo with Arab League Secretary-General Amr Musa.
He said he did not exclude the possibility that "Israeli fingers" were behind the blast in a bid to undermine Palestinian national unity backed by Syria.
Israel has accused Syria of involvement in the Friday night attack which killed four people and cast a long shadow over tentative peace moves in the Middle East.
Shara also held talks with Egyptian President Husni Mubarak on Sunday in Cairo's latest bid to defuse the crisis facing Damascus, under international pressure to withdraw from Lebanon.
Chirac discussed the situation in
Lebanon and Syria with Mubarak
Meanwhile, French President Jacques Chirac, whose country co-sponsored with the United States a UN Security Council resolution urging an end to all foreign interference in Lebanon, also spoke by phone with Mubarak on the issue.
"President Chirac wanted to know President Mubarak's view on the ways to rapidly implement Resolution 1599 on Lebanon," a presidential spokesman said.
The meeting between Shara and Mubarak came just four days after Egypt dispatched intelligence chief Umar Sulaiman to Damascus for talks to "contain the situation in Syria and Lebanon within an Arab framework."
Their talks were expected to cover the situation in Lebanon following the murder of ex-prime minister Rafiq al-Hariri on 14 February, and pressure Damascus to withdraw its troops from the country.
The opposition in Beirut has accused the pro-Syrian government of being behind Hariri's death.