When he visits Israel next month, US President Barack Obama will tell Prime Minister Benjamin Netanyahu that a “window of opportunity” for a military strike on Iran will open in June, according to an Israeli TV report Monday evening.

Obama will come bearing the message that if diplomatic efforts and sanctions don’t bear fruit, Israel should “sit tight” and let Washington take the stage, even if that means remaining on the sidelines during a US military operation, Channel 10 reported. Netanyahu will be asked to refrain from any military action and keep a low profile, avoiding even the mention of a strike, the report said, citing unnamed officials.

In London Monday, Secretary of State John Kerry said an Iran with nuclear weapons was “simply unacceptable” and warned the time limit for a diplomatic solution was running out.

“As we have repeatedly made clear, the window for a diplomatic solution simply cannot remain open forever,” said Kerry, on his first international tour as America’s top diplomat. “But it is open today. It is open now and there is still time, but there is only time if Iran makes the decision to come to the table and to negotiate in good faith.

“We are prepared to negotiate in good faith, in mutual respect, in an effort to avoid whatever terrible consequences could follow failure, and so the choice really is in the hands of the Iranians. And we hope they will make the right choice,” Kerry added.

A fresh round of high-level diplomatic talks were set to begin Tuesday in Kazakhstan — the first since last June’s meeting in Moscow failed to convince Iran to stop enriching uranium to a level close to that used for nuclear warheads.

Two weeks ago, Netanyahu said he was looking forward to Obama’s visit and insisted that he enjoyed a positive relationship with the American president, despite reports to the contrary. 

“We worked together closely, closer than how it may look. We worked together on security, diplomacy and intelligence,” he said, warning that Iran’s nuclear weapons program “continues unabated” and that “they’ll soon have enough material to produce a nuclear bomb.”

Netanyahu said earlier this month that he and Obama had agreed on three key areas of consultation during the presidential visit — thwarting Iran’s nuclear drive, grappling with the instability in Syria and the risks of WMD there falling into rogue hands, and the Israeli-Palestinian conflict.

The Associated Press contributed to this report.