Updated

The State Department on Friday night called for Israelis and Palestinians to show mutual restraint and avoid actions that could increase tensions following the shelling of civilian Palestinians along a beach on the Gaza Strip.

Seven people attending a picnic died in the incident. In response, Hamas militants called off a truce with Israel that had been in effect since February 2005. Hamas, which the U.S. considers a terrorist organization, leads the Palestinian government.

CountryWatch: Israel

The U.S. expressed regret for the killing and wounding of the Palestinians in Gaza and noted that the Israeli government had also issued a statement of regret and had launched an investigation, State Department spokesman Sean McCormack said in a statement.

The targets of Israeli artillery on Friday were suspected Palestinian rocket-launching sites. An Israeli airstrike on Thursday killed a militant commander in the Palestinian government.

Israel suspended artillery fire while the investigation into the deadly beachside attack continues, a move the U.S. welcomed, McCormack said.

"We call on the Palestinian Authority to prevent all acts of terrorism, including the firing of missiles and rockets from Gaza," McCormack said.

The U.S. has been in contact with Palestinian Authority President Mahmoud Abbas and the government of Israel and will continue to monitor the situation closely, McCormack said.