France has asked Qatar, which has close links with Hamas, to use its influence with the Palestinian Islamist group to reach a ceasefire in the conflict in Gaza, a French diplomatic source said on Friday.

Israel intensified its land offensive in Gaza with artillery, tanks and gunboats on Friday and warned it could "significantly widen" an operation Palestinian officials said was killing an increasing number of civilians.

Israel briefly held fire on Tuesday after Hamas rejected a truce plan proposed by Egypt. Hamas wants Israel to lift border restrictions that have deepened Gaza's economic hardship and unemployment.

Qatar emerged as a leading supporter of Islamist groups after Arab Spring protests that began in 2011. It sees the standoff as a chance to play a key role in trying to broker a ceasefire.

Qatar's state news agency said Foreign Minister Khaled al-Attiyah had received a phone call from French Foreign Minister Laurent Fabius on Friday in which they "searched for ways to reach an agreement on a ceasefire".

A French diplomatic source told Reuters: "The minister did just speak to him (al-Attiyah) a few minutes ago and asked him to use his influence on Hamas to reach a ceasefire."

Qatar hosts a number of exiled Islamists across the Middle East, including Hamas leader Khaled Meshaal.

French Foreign Minister Laurent Fabius told reporters on Friday that Palestinian President Mahmoud Abbas wants France to lobby Qatar and Turkey-Hamas allies- to pressure the Islamist movement into accepting the truce. The two men met on Friday at Cairo airport before Abbas left for Turkey.

"He (Abbas) asked me to contact the Turks and Qataris with whom we have good relations, because they themselves can exert a particular influence on Hamas," Fabius said.

"There can be influences that I hope can let Hamas accept the ceasefire that it has refused," Fabius said, adding that he would call both countries' governments to press the issue.

In Turkey, Abbas held a news conference with Turkish President Abdullah Gul in Istanbul. "Israel accepted the ceasefire proposal. We (the Palestinians) must also accept it so that we can put the Israeli side at unease", AFP quoted Abbas as saying.