How to Automate jenkins build based on assembla merge to request to a branch

Question

I wish to do the automate build in jenkins based on "assembla"

i have installed "assembla build trigger" plugin in jenkins and configured it. i have enabled the " build merge request" under " assembla build trigger" plugin it automates the build when the merge request has made on assembla;

But i need is jenkins should automate the build only when merge request to particular branch (Eg, development) not to merge request on the repo( on any branch)

But here the build get automates when the merge request was done in repo in any branch;

same way i have enabled the "build push" under the same " assembla build trigger " ; which will automate the build only when

#git push branch 

is happened .

But we will use "merge request" and " merge branch " in assembla to get pushed to branch.