Iran’s parliament speaker warned Sunday that lawmakers could call for stepped-up atomic work if the West presses too hard for concessions in ongoing nuclear negotiations.

The message from Ali Larijani — less than a week after talks resumed — appears aimed at both envoys from the West and Iran’s negotiation team, which is led by Foreign Minister Mohammad Javad Zarif. It also highlights the political jockeying inside Iran between backers of moderate-leaning President Hassan Rouhani and hard-liners wary of his outreach to Washington.

Larijani’s comments follow appeals by some members of the U.S. Congress to tighten sanctions on Iran despite the nuclear negotiations and historic diplomatic breakthroughs last month, including President Barack Obama’s telephone call to Rouhani. Larijani, meanwhile, told Iran’s representatives that parliament would not permit world powers to impose “special measures” on the country beyond the obligations laid out by the U.N. treaty overseeing nuclear activity, such as U.N. monitoring and inspection.

Iran’s ruling clerics approve all major policies and decisions, but parliament holds enough clout to potentially disrupt talks in response to Western demands to curb the program. Such resistance from Iran’s parliament could throw doubts on Rouhani’s ability to strike a deal with world powers in the same way that protests in Congress could stand in the way of potentially easing sanctions.

On Sunday, Rouhani told a Cabinet meeting to be careful about foreign enemies’ plans for damaging unity in the country, the official IRNA news agency reported. Rouhani said Israel is trying to undermine the ongoing nuclear negotiations.

“Zionists were resorting to sabotage and trouble-making inside or outside the country whenever Iran was achieving a success,” Rouhani was quoted as saying.

Details from last week’s talks remain tightly guarded, but short-range priorities have been made clear. The U.S. and allies seek to roll back Iran’s highest-level uranium enrichment, which is several steps away from weapons grade. Iran wants the West to start withdrawing sanctions, which have hit Iran’s vital oil exports.

The next round for talks is scheduled in Geneva for Nov. 7-8 between Iran and a six-nation group, the permanent U.N. Security Council members and Germany. The West and others fear that Iran could eventually produce a nuclear weapon. Iran insists it only seeks reactors for energy and medical use.

The semiofficial Fars news agency quoted Larijani as saying that Iran’s nuclear program cannot be pushed beyond the requirements of the U.N.’s nuclear non-proliferation treaty, or NPT, which Iran has signed.

“Iranian negotiators should be fully aware of this,” Larijani said. “If parliament feels another powerful party has a double-standard and unjustifiable attitudes, it will approve necessary measures on amount and diversity of nuclear activities.”

Larijani did not elaborate, but said there is “no room for trust” yet with the U.S.