Talks to agree a ceasefire between Israel and Hamas in Gaza were “not very promising” in recent days, mediator Qatar has said.
Prime Minister Mohammed bin Abdulrahman Al Thani said he remained optimistic, but added “time is not in our favour”.
It comes as Israel’s prime minister said he would press ahead with plans for a Rafah ground invasion, despite growing international pressure.
Hamas has blamed Israel for a lack of progress in achieving a ceasefire deal.
Talks have been taking place in Cairo as senior officials from the US, Israel, Egypt and Qatar meet to try to broker a pause in fighting.
“The pattern in the last few days [is] not really very promising but, as I always repeat, we will always remain optimistic and will always remain pushing,” said Sheik Mohammed, speaking at a meeting of world leaders at the Munich Security Conference.
“I believe in this agreement we are talking at a bigger scale and we still see some difficulties on the humanitarian part of these negotiations,” he added.
But he said a truce should not be dependent on a deal to release the hostages held by Hamas.
“This is the dilemma that we’ve been in and unfortunately that’s been misused by a lot of countries – that in order to get a ceasefire, it’s conditional to have the hostage deal,” he said.
Israeli Prime Minister Benjamin Netanyahu said he sent negotiators following a request from US President Joe Biden, but added they did not return for further discussions because Hamas’s demands were “delusional”.
The group has laid out a series of demands, including the exchange of hostages for Palestinian prisoners, full withdrawal of Israel’s forces and an end to the war after a 135-day pause in fighting, broken into three phases.
Israel launched its military offensive after Hamas-led gunmen killed at least 1,200 people and seized 253 hostages in a surprise attack on its territory on 7 October.
The Hamas-run health ministry says more than 28,800 people, mainly women and children – have been killed in Israel’s campaign.
At a news conference, Netanyahu reiterated his goal of destroying Hamas and said his forces would continue to fight until Israel achieves “absolute victory.”
He said those urging opposition to military action in Gaza’s southernmost city of Rafah were effectively telling the country to “lose the war”, adding that his troops would move into Gaza’s southernmost city even if a hostage deal was reached. The city of Rafah, where about 1.5 million people have fled.
Early in the war, when Israeli forces advanced on northern cities, Israel directed Palestinians to seek refuge in Rafah.
Israeli authorities said this week they wanted civilians to relocate to what they call the “humanitarian zone” – a narrow strip of mostly agricultural land along the Mediterranean called Mawasi.
President Biden has urged Israel not to launch an offensive against Rafah without a plan to ensure the safety of civilians.
Mr Netanyahu is also facing domestic pressure to bring home the hostages remaining in Gaza.
Thousands of protesters gathered in Tel Aviv on Saturday to call for early elections, which are not scheduled to be held until 2026. Israel’s prime minister dismissed similar calls from within his ruling Likud party to hold elections immediately after the conflict with Gaza ends, saying it would “immediately divide us”.
Hamas, meanwhile, has accused Israel of a lack of progress in reaching a ceasefire and threatened to suspend participation unless relief supplies arrive in northern Gaza. Aid agencies say they are increasingly concerned about a lack of food, water and medicine in the area.