There is a huge problem with a "call to engagement": It simply cannot work, and worse, it is misleading as it seems to offer the hope that it might.
There are many reasons why it cannot work with Iran: The largest is that it ignores the internal political dynamic (The Guardian Council's desire to retain its shaky hold on power) that is the prime motivator for Iran's behavior. In other words, the dynamic is internal, not external, and it is one that we cannot affect via "engagement".
The Guardian council are not fools: they have not been inept and confrontational for no reason. Their reason is to generate external crises to shore up domestic support.
Also, "engagement" and above all "trade" are so often cited as an alternative to rivalry and conflict. The problem there is that they do not work, or, more precisely, they create what they seek to avoid. Europe, for example, is very "engaged" with Iran, both economically and politically. It isn't working. All it has succeeded in doing is making the West look weak and spineless. Let us also look to history as we judge the efficacy of engagement and trade. What was Japan's largest trading partner in Dec 6th, 1941? The US. What were Germany's #1 and #2 trading partners on Aug 30th, 1939? France and the UK. What was Germany's largest trading partner and military partner on June 21st, 1941 (the day before Germany launched operation Barbarossa? The USSR.
If we want to get serious about Iran (the same Iran that has topped the Terror-supporting states list for four consecutive US administrations) the first thing to address is their nuclear program, as everything else is secondary. Given the Guardian council's preposterous claims that they seek nuclear power for energy, combined with the vast amount of internal dissent in Iran, the most obvious strategic opening is to exploit those circumstances. The regime has set it self up for a massive backlash, if it can be shown to be misleading the people, to their detriment. The key here is Gasoline. Iran does not have exploitable reserves of Uranium, so they can never have (as they have claimed as their goal) a nuclear energy program not reliant on foreign sources. This fact has been ignored by the West. Further, so has the Iranian Gasoline situation: for all their claims of needing nuclear power to reduce their energy vulnerability, Iran, which has some of the world's greatest oil reserves, has never bothered to build the refining capability to produce gasoline sufficient for their needs. As a result, Iran is one of the world's largest importers of Gasoline. Were that supply (much of it currently from Venezuela, one of the few countries with sufficient surplus refining capacity) cut, Iran would face a fuel crisis, and the Guardian Council would be made to look like fools for pursuing nuclear power while ignoring Iran's fossil-fuel refining capability. Thus, their internal dissent problem might be exploited.
The only answer to the Iranian situation is greater pressure, either what I outline above or other means. Engagement isn't the answer, because it ignores the causal factors.
We also don't have much time: The further along their nuclear program progresses, the less effect an air strike, even if successful, will have upon it. We have no need to invade Iran, and we certainly do have the military ability to conduct air strikes, but the window of opportunity is closing fast.