European objections have forced the United States to backtrack on plans to stage a two-day conference in Poland focused on building a global coalition against Iran.

The conference is now being described as a wider brainstorming session about the Middle East.

In announcing the summit earlier this month, the US secretary of state, Mike Pompeo, had explicitly said the summit’s purpose was to focus on Iran’s influence and terrorism in the region.

But the joint official announcement of the summit did not mention Iran, instead highlighting issues connected with Iran – “terrorism and extremism, missile development and proliferation, maritime trade and security, and threats posed by proxy groups across the region”.

The change of emphasis follows signs that many European countries, including the EU foreign affairs chief, Federica Mogherini, will avoid the two-day event on 12 and 13 February, and instead head to the Munich security forum later in the week.

The US has been trying to persuade the EU to drop its support for the 2015 Iran nuclear deal, and has been using the threat of US secondary sanctions to press EU firms not to trade with Iran.

The UK is one of the countries most conflicted about attending the Polish conference since the UK is traditionally close to both Poland and the US, but has stood by the Iran nuclear deal.

The broadening of the agenda may be designed to make it easier for the UK to attend. Jonathan Cohen, US representative at the UN, described the scope of the discussion as “much broader than any one country or set of issues”. He said it would be a “global brainstorming session” and stressed that it was “not the venue to demonise or attack Iran.”

Issues such as the humanitarian crises in Syria and Yemen, missile development and cyber security would be discussed, Cohen told the UN security council.

The Polish envoy to the UN, Joanna Wronecka, also said the ministerial conference in Warsaw would bring “added value to the efforts to peace in the Middle East by creating a positive vision to the region”. She said 70 countries all over the world had been invited but stressed the summit would address “a range of horizontal issues that touch on the whole region. We do not intend to focus on particular countries during the conference”.

Poland’s deputy foreign affairs minister Maciej Lang travelled to Iran to reassure Tehran this week, and Poland on Wednesday said it may yet add Iran to the invitation list.

Iran is sceptical that the US will be interested in anything other than a two-day Iran-bashing fest.

Russia has already said it will not attend the summit, and a wider boycott, or attendance by low-level officials, would demonstrate the United States’ international isolation.

Iran’s foreign minister Javad Zarif tweeted that his country had welcomed over 100,000 Polish refugees during the second world war. “[The] Polish government can’t wash the shame: while Iran saved Poles in the second world war, it now hosts a desperate anti-Iran circus.”

European states have remained largely remained united behind the nuclear deal, even if its patience with Iranian ballistic missile tests is wearing thin.

The summit may also serve to highlight the inability of the EU to assemble a “special purpose vehicle” (SPV) meant to serve as a back channel to handle financial transactions and bypass US sanctions on Iran.

The SPV has been delayed for months.

The new EU-Iran alliance has suffered due to accusations that Iran has been behind assassination plots on European soil, a matter being closely followed up by the Dutch and Danish governments.