We destroyed Serbia's economy and later infrastructure with sanctions and bombing. They are doing whatever they have to get on their feet re the economy, as are we here in the US.
Add to that the fact that they have a president, Boris Tadic, who was trained by John McCain's IRI to do what he is told.
Ever look at who else trades with Iran? It includes us!
And then there are those who have directly invested in Iran in recent years:
Firms from over 50 countries have invested in Iran, with Asia and Europe receiving the largest share. Asian firms have invested over $11.6 billion in 190 Iranian projects, with those from the United Arab Emirates (UAE) leading the way, followed by Singapore, Indonesia and Oman. Over 20 European countries, particularly Germany, the Netherlands and Spain, made investments worth over $10.9 billion in 253 projects. The UK, Turkey, Italy and France also have had a great share in Iranian investments. Companies from Canada, Panama, the USA and Jamaica are also involved in seven economic projects in Iran, valued over $1.4 billion. Investors from Mauritius, Liberia and South Africa have invested a combined total of $8 billion in Iran. In addition, Australia has invested $682 million in an Iranian project.
And then there is Israel's allies, Iran's trading partners Serbia is also the second largest supplier of arms and munitions to Israel.
Point is that for all the rhetoric, everybody is "trading with Iran" including us.
A better gauge of "intentions" is where Iran is investing her money and why. Albania calls for Iran investment
Even assuming that your “everyone does it” argument is applied correctly, it doesn’t contradict my point.