JERUSALEM (AP) _ A newspaper reported today that Israeli tanks fired on battling Shiite Moslem militiamen in south Lebanon, killing at least 10 guerrillas and wounding 15.

An army spokesman refused to confirm or deny the report, but Defense Minister Moshe Arens warned that Israel would take a role in the fighting if the battles threatened Israeli interests.

The daily newspaper Yediot Ahronot reported that Israeli tanks opened fire Monday on the village of Jarjou, a site of rival Shiite militia fighting just beyond Israel's self-proclaimed security zone in south Lebanon.

At least 10 fighters of the rival Hezbollah and Amal militias were killed in the shelling and about 15 were wounded, the newspaper said. It did not cite sources for the report.

In a statement published in Beirut today, Hezbollah also reported Israeli fire aimed at militia fighters Monday. It said three of its fighters were killed and two wounded. The firing came from an outpost of Israeli-backed militiamen, about a half-mile from Jarjou, the statement said.

Both protagonists in the Lebanese dispute are enemies of Israel dating to the Jewish state's three-year occupation of south Lebanon, which began with a June 1982 invasion to drive out Palestine Liberation Organization guerrillas.

Israel carved out a 6- to 10-mile-wide ''security zone'' along the Lebanese border after it withdrew the bulk of its soldiers. The zone is intended to prevent guerrilla raids across the border.

The fighting between Hezbollah and Amal erupted July 16, the latest stage in an intermittent 3-year-old battle to gain mastery over Lebanon's Shiite community. Some 186 people have been killed in these artillery battles and 560 wounded, by Lebanese police count.

Much of the latest combat has occurred on the rim of the Israeli security zone.

Arens told Israel radio ''there is a danger that the situation will get worse and endanger our interests.''

Earlier, Arens told Yediot Ahronot: ''If the combat reaches a point in which we see that our interests are endangered ... in other words when the situation becomes intolerable from our standpoint - there will be no choice and we will get involved.''

A source in south Lebanon, who spoke on condition of anonymity, said the Israelis appeared to be warning the militiamen to steer clear of the border rather than signaling intentions to intervene.