German Foreign Ministry  expressed its concern over the violence in Gaza and called on all participants to avoid further escalation, DW reported. 
"The incident shows how absolutely necessary it is to resume negotiations," it said in a Twitter statement.

At least 15 Palestinians were killed on Friday: Two of them by Israeli tank fire, according to the Gaza Health Ministry. The same source said 400 people were wounded by live Israeli gunfire and others were struck by rubber bullets or treated for the effects of tear gas.

The violence broke out after tens of thousands of Palestinians, including women and children, gathered at five points along the fenced border of the blockaded territory. Protesters called for the return of tens of thousands of refugees who were expelled or fled during the war around Israel's creation in 1948.