By Steve Holland and Enas Alashray WASHINGTON/CAIRO, July 11 (Reuters) - President Donald Trump said the U.S. and Iran had agreed to continue talks despite an escalation of hostilities this week but he declared that the ceasefire reached between the two sides last month was over. The United States also stepped up demands on Friday that Iran stop attacks on ships in the Strait of Hormuz, where recent hostilities have pushed oil prices higher, a politically sensitive issue for Trump ahead of Novem