wingsandsword
Legend
Mon Cal didn't go into open rebellion until after the Battle of Yavin, and the Interdictors are built on a much smaller frame than the Imperial Star Destroyer. An Interdictor Cruiser is 600 meters long, compared to the 1600 of an ISD, or 1200 of a typical Mon Cal MC80, and mounts 4 gravity well projectors (although they do tax the power output of the Interdictor heavily).They probably wouldn't have much ability to make use of it, once Mon Calamar gets blow'd up by the Death Star. Remember, the Imperial interdictors are based on the Star Destroyer design and have significantly less firepower, so the ones they mount seem to take up a crapload of resources.
Without the Mon Calamari shipyards, they're limited to making a few on what capital ships they can scrounge up.
Brad
The Empire did build some other ships with Interdiction technology, and one of the first was an ISD with interdiction hardware present at the blockade at Yavin as Vader's flagship, but they were much less prominent.
Upon a little more research though, apparently they have retconned the events of Battle for the Golden Sun to having taken place before Yavin, since the earliest canonical appearance of an Interdictor is 2 years BBY.