The Israeli military threatened with a "stronger response" to protests along border with the Gaza Strip on Saturday, only a day after it murdered 15 Palestinian protesters and injured more than 1,400 protesters.

The Israeli army killed the civilians during "Land Day", an annual Palestinian commemoration of the deaths of six Arab citizens of Israel killed by Israeli forces in 1976 during demonstrations over government land confiscations in northern Israel.

"[If] violence drags on along the Gaza border, Israel will expand its reaction to strike the terrorists behind it," army spokesperson Brig. Gen. Ronen Manelis said in a statement.

The spokesperson said Israeli troops so far "restricted" its response to the border fence with Gaza, but "will go after militants in other places too" if attacks continue.

On Friday, UN Secretary-General Antonio Guterres called for an independent and transparent investigation into the deaths along Gaza border.

Friday's rallies were the start of a six-week protest that culminates on May 15, the day the Palestinians call as "Nakba", or "Catastrophe", when Israel was created.

The demonstrators are demanding that Palestinian refugees be allowed the right of return to towns and villages which their families fled from, or were driven out of, when the occupying state of Israel was created in 1948.