The Trump administration has an easy way to disprove this claim. But they won't release the language they signed.
But Trump's social media rants make it seem like this is correct, which is a horrifying thing
A last-minute addition to the Iran-US understanding says any war or military operation in Iran or against Iran’s regional allied groups, including Lebanon, would halt negotiations on a final agreement, IRGC-affiliated Tasnim news agency reported, citing a source close to Iran’s negotiating team.
“The important meaning of this development is that if war or any military operation, such as assassination and so on, takes place in Iran or the resistance front, including Lebanon, then under the memorandum of understanding, no negotiations for a final agreement will take place, and naturally the implementation of the memorandum of understanding, including the reopening of the Strait of Hormuz, will be halted under Article 13,” Tasnim quoted the source as saying.