Prime Minister Benjamin Netanyahu has reportedly informed the German embassy that he would not meet with visiting German Foreign Minister Sigmar Gabriel if the latter does not cancel plans to meet with the left-wing Breaking the Silence organization, Israel Radio reported.

Gabriel responded by saying it would be “regrettable” to cancel his meeting with the prime minister, but he refused to change his plans to meet with the anti-Israel and anti-IDF group.

Deputy Foreign Minister Tzipi Hotovely defended the move, saying the organizations in question “slander the State of Israel on the international stage.”

“”It is important for the foreign ministry to let European officials know, in no uncertain terms the urgency with which Israel views the issue of foreign state funding to these organizations.

“We expect our friends around the world to show sensitivity on these issues,” she said.

Gabriel arrived in Israel from Jordan on Monday and will meet President Reuven Rivlin today before continuing on to Ramallah for talks with Palestinian Authority Prime Minister Rami Hamdallah.

Political reaction to Netanyahu’s threat was quick in coming. Yesh Atid Chairman Yair Lapid, who plans to challenge Netanyahu for the prime ministership in 2018, also said Gabriel should not meet with Breaking the Silence, but added that Netanyahu shouldn’t cancel the meeting, though he affirmed that the premiere’s displeasure was justified.

“(Netanyahu is) 100 percent right! If (a foreign diplomat) went to Germany and met with the radical left, Merkel would be just as angry,” Lapid wrote on Twitter.

Opposition Leader Yitzhak Herzog, who is also scheduled to meet with Gabriel, also called on Netanyahu not to cancel the meeting, saying the move would strike a “serious blow” to Israel-Germany ties.

“This ultimatum … is a serious blow to Israel’s ties with the country with the the largest economy in Europe and is a true friend,” Herzog said.