Iran has warned it may “seriously reconsider” its commitments to the UN atomic watchdog if European parties to a nuclear deal trigger a dispute mechanism that could lead to fresh sanctions.

The speaker for the Iranian parliament, Ali Larijani, told a press conference in Tehran on Sunday: “If they use the trigger [mechanism], Iran would be forced to seriously reconsider some of its commitments to the International Atomic Energy Agency. If they think doing so is more beneficial to them, they can go ahead.”

The threat to trigger sanctions has come after the Iranian government has taken a series of deliberate steps away from the 2015 nuclear deal, which it says are intended as a reprisal for Europe’s failure to deliver on commitments to boost trade.

Iran has also been frustrated by Europe’s refusal to defy the threat of US sanctions against any European company that trades with Iran.

A mechanism known as Instex developed by Europe to sidestep sanctions received a boost at the weekend when six more EU countries said they would join. Instex is a bartering system devised to avoid the reach of the US, but Iran is less interested in the number of EU countries signed up than the fact that no deals are being made under the mechanism.

Israel on Sunday attacked the six new signatories, saying it encouraged Tehran’s repression of protests. “Belgium, Denmark, Finland, the Netherlands, Norway, and Sweden could not have picked worse timing,” the Israeli foreign ministry said in a statement.

“The hundreds of innocent Iranians murdered during the latest round of protests are rolling in their graves.”

The London-based human rights group Amnesty International said 161 demonstrators were killed in the protests over petrol price rises, a figure disputed by Iran.

Larijani’s warning came as he fuelled speculation he would run for the post of president in the 2021 elections by announcing he would not stand in parliamentary elections in February next year.

Larijani was speaking on the day registration for standing in the parliamentary elections opened. All candidates have to be vetted by the Guardian Council, a theological body. A spokesman for the council, Abbas Ali Kadkhodaei, said it may be less likely to debar candidates than before.

He said: “We don’t consider ourselves immune from criticism. We may also accept that mistakes have been made in the past. But for the next legislative elections we are trying to reduce our mistakes and respect the rights of candidates.”