United Nations, May 16 : UN Secretary-General Antonio Guterres has voiced grave concerns over civilian casualties and the destruction of media offices in the Gaza Strip by Israeli strikes, said his spokesman Stephane Dujarric. The Secretary-General is dismayed by the increasing number of civilian casualties, including the death of 10 members of the same family, as a result of an Israeli airstrike on Friday night in the al-Shati camp in Gaza, Xinhua news agency quoted Dujarric as saying in a statement on Saturday. The UN chief is also deeply disturbed by the destruction by an Israeli airstrike on Saturday of a high-rise building in Gaza City that housed the offices of several international media organisations as well as residential apartments, said the statement. Guterres reminds all sides that any indiscriminate targeting of civilians and media structures violates international law and must be avoided at all costs, Dujarric's statement said. The 12-storey al-Jalaa Building, where the offices of the Associated Press, Al-Jazeera and other media outlets are located, was levelled in an Israeli airstrike. Israel claimed the building housed Hamas military intelligence elements. Tensions between Israel and the Islamic Hamas movement, the worst since 2014, have continued unabated in the Gaza Strip with no sign of any ceasefire between the two sides to end the violence. The Hamas-run Ministry of Health said that 122 Palestinians have been killed, including 31 children and 20 women, and 900 others injured since Monday in the Gaza Strip. The Israeli army said Gaza militant groups have fired more than 1,750 rockets at Israel. The rockets fired from Gaza killed at least nine Israelis and wounded 200 others. /IANS