If you are working in a multi culture enviornment, what tools and techniques you will use to overcome the cultural barriers?

Project Managers need to be sensitive towards cultural differences, Religion. There is a high chance of misunderstandings due to difference in language and culture. A sarcasm by a US or other Western team member might be viewed abusive by Asians. 

It is important for Project Manager to have regular touch base meetings with respective leads and win the trust by listening to their issues/concerns and solve them. If the teams are located geographically different locations, Travel to the other locations to meet with team members face to face; bring in leads from there for the Project kick off meetings. 

Have frequent team building activities to allow social time that will help the team members open up with each other..

Send out the meeting minutes after project meetings to avoid misunderstandings; or have a follow-up talk after important communications. 

Set groundrules for team meetings...

There are more techniques available, but I wrote something based on my own experiences which worked for me...

Managerial skills for cultural diversity is very important International Project Management. It is essential to know the real information about about nations and thier culture.  Migt be owel be Mr. Wisdom in one nation but it is the symbol of foolish in another nation. Same example with donkey. The most imprtant think is the respect of religion, culture, feestival and language. Some nations are future oriented and some are present oriented. So, determination of their approaches are very important.

Open Communication, extra activities (e.g. outing, dinner party, sports events) ,Regular feedback and meeting with staff, resolve conflicts by listen both parties, flat culture of organisation.

I am trying to hire people close to this environment to know their cultures and facilitate to convey our remarks to residents without disturbing them

Being optimistic,broad minded,open forum,diplomacy and planning.

Welcome to diversify communication methods and create them to suit different cultures while ensuring integration of different values ​​and professional benefits to achieve the established goals

Most answers I've seen are linked to a managerial approach as it might be a mandatory procedure or protocol. Along the experience in a cross-cultural environment, unfortunately you can't force anything. It's about let people be themselves since their recruitment, make employees very much aware of the fact of cross-cultural relations. I had good experiences and bad experiences. Definetely employees and employers, managers and dependants must behave as it's intended to be in the country they are located. After that, full dialogue intention, and most important gender equity and respect, even if it gets difficult in some countries. Respect all preferences but make a personal effort into learn the other's perspective, be curious but not impertinent, be comprehensive and try to give in a little.