ISTANBUL — Secretary of State John Kerry said Sunday that he had urged Prime Minister Recep Tayyip Erdogan of Turkey to put off his planned visit to Gaza to avoid disrupting efforts to revive peace talks between Israel and the Palestinians.
Erdogan has said he plans to visit the Hamas-controlled Gaza Strip in May after a planned trip to Washington, but the move has raised concerns. Both Israel and the Palestinian president, Mahmoud Abbas, who is based in the West Bank, are opposed.
“We have expressed to the prime minister that we really think that it would be better to delay,’’ Kerry said in a news conference here.
‘‘The timing of it is really critical with respect to the peace process that we are trying to get off the ground,’’ Kerry said. ‘‘We would really like to see the parties begin with as little outside distraction as possible.’’
Kerry, who has made three trips to the Middle East since becoming secretary of state, has been trying to lay the groundwork for renewed peace talks between Israel and the Palestinians.
The secretary of state also said he would press for the quick delivery of an additional $123 million in nonlethal US aid to the Syrian opposition.
He recently told Congress that the window for a two-state solution — the establishment of a Palestinian state living in peace with Israel — is closing, and that it would be imperative to make progress in the next two years.
Toward that end, Kerry met in Istanbul on Sunday with Abbas. The two reportedly discussed ways to improve the Palestinians’ living conditions as one way to improve the climate for a resumption of peace talks.
US efforts to get the talks off the ground have been complicated by the resignation this month of Salaam Fayyad, the Palestinian prime minister. Kerry acknowledged that Fayyad’s resignation was a disappointment but said that he hoped a worthy successor would be found.
At the same time, US officials have urgently tried to head off any upset in the efforts to restore Israeli-Turkey relations.
President Obama brokered a rapprochement between Israel and Turkey last month during his visit to Israel. The aim was to foster the full resumption of diplomatic relations between the two states, including the return of ambassadors.
Ties between Israel and Turkey suffered a serious setback in 2010 when the Israeli military intercepted the Mavi Marmara, a Turkish ship that was trying to run the naval blockade on supplies to Gaza, and met resistance on board. Nine activists — eight Turks and one American of Turkish descent — were killed.
Prime Minister Benjamin Netanyahu of Israel apologized for the raid during Obama’s trip in March, and a team of Israeli officials arrived in Turkey on Sunday to discuss compensation for the families of those killed or wounded.
Erdogan is scheduled to visit Washington on May 16, and American officials are eager to see substantive process by then. Kerry said Erdogan’s trip and meeting with Obama ‘‘will be an important next step in this ongoing dialogue.’’
Kerry travels next to Brussels, where he will attend a meeting of NATO foreign ministers on Tuesday.
In other comments Sunday, Kerry provided new details about the sort of nonlethal aid the United States is planning to provide the military wing of the Syrian opposition after a meeting Saturday with the opposition and the 11 nations that are supporting it.
Kerry said he would press for the quick delivery of the aid so that it would be weeks, and not months, for it to be provided to the opposition.
In late February, Kerry announced that the United States would begin providing food and medical supplies to the armed opposition. But that aid has yet to be provided. A US official said that it would be delivered by April 30.
At the Istanbul conference, he announced that the Obama administration would double its nonlethal assistance to the Syrian opposition with an additional $123 million in supplies.
The aid could include for the first time armored vehicles, body armor, night vision goggles, and other defensive military supplies.
The precise equipment is to be determined in discussions with the Supreme Military Council, as the military wing of the Syrian opposition is known.
‘‘I can’t tell you how quickly it will change things on the ground,’’ Kerry said Sunday. ‘‘I can promise you that as soon as I return to Washington, I am going to press as hard as I can’’ to get it to the opposition within a matter of weeks.
‘‘This has to happen quickly, it has to have an impact,’’ he added.
The additional aid will bring total nonlethal US assistance to the opposition to $250 million since the fighting began more than two years ago. Kerry said the aid ‘‘underscores the United States’ firm support for a political solution to the crisis in Syria and for the opposition’s advancement of an inclusive, tolerant vision for a post-Assad Syria.''
The US pledge was the only tangible offer of new international aid made public at the meeting of the foreign ministers of the donor countries. It fell well short of what the opposition has been seeking: weapons and direct military intervention to stop the violence that has killed more than 70,000 people.