I think if it helps leverage a better agreement then absolutely, use the threat of a travel ban.
We have first hand experience with the Chinese that they'll act responsibly and work with Pakistan in the event of an outbreak, so I don't think there is an issue there, but we should look into formalizing a framework for dealing with disease outbreaks in the future to prevent any miscommunication.
What measures? Saudi Arabia is a host country for pilgrims just like Iran is - if the Saudis and Iranians want to come up with measures that restrict the entry of pilgrims, there isn't much we can do. And on the subject of the Saudis, we should probably formalize a framework with the GCC countries along the lines of what has been proposed with the Iranians and Chinese given the large numbers of Pakistani pilgrims that go to Saudi Arabia & travel/work in GCC countries every year.
These are the kinds of positive and constructive measures we should be focusing on right now. We've maintained a relationship with Afghanistan, despite all the double crossing, hatred, claims on Pakistani territory and support for terrorism against Pakistan they've engaged in, so we're unlikely to take harsh measures against Iran which has engaged in a fraction of that kind of anti-Pakistan behavior.