JERUSALEM—The border between Israel and the Gaza Strip remained tense Sunday after attacks over the weekend that showed how fragile the cease-fire is since the summer’s war between Israeli troops and Hamas.

A rocket launched into Israel on Friday drew an Israeli airstrike in Gaza, the first since an August cease-fire, and the two sides traded strong rhetoric even as efforts were made to avoid an escalation.

During a visit to Israel’s south Sunday, Defense Minister Moshe Yaalon said the rocket – the third fired into Israel since the cease-fire – was launched by a rogue Palestinian organization but that that factor was irrelevant. “It is clear that Hamas is responsible for what happens in Gaza,” he said of the militant group that rules the coastal enclave.

Yaalon added that Israel had sent Hamas a message through Egyptian contacts as well as with an airstrike to convey that it would not tolerate rocket fire while expressing its interest in calm.

In Gaza, Hamas spokesman Sami Abu Zuhri called the Israeli bombing of a cement factory a “dangerous escalation” and a “foolish act.” At the same time, senior official Mousa Abu Marzook stressed Hamas would remain “committed to the cease-fire” as long as Israel is.

While the truce that stopped a 50-day war largely holds, Israeli media reports that Hamas has been test-firing rockets toward the Mediterranean and rebuilding the military tunnels destroyed during the war.

However, Yaalon said that contrary to the situation after previous military engagements, Israeli and Egypt have stopped arms and other supplies for Hamas from Iran and Libya.

On the Israeli side, border area residents called attention to their concerns in a protest outside the Defense Ministry on Saturday night.