I wonder if this question can be answered with reference to the way that Venice is presented as a society made up of different social classes but also different ethnic groupings. Of course, the central social "clash" would be the way in which Jews are treated and abused by Venetian society, as is shown through Antonio's mistreatment of Shylock. Venice is presented as a society that is definitely not characterised by harmony and unity. Consider the charges that Shylock brings against Antonio in Act I scene 3, which is of course when Antonio tries to borrow money from him:
You call me misbeliever, cutthroat dog,
And spit upon my Jewish gaberdine...
Such lines speak of blatant abuse and division between the various social elements of Venetian society, which was famed as a centre for merchants and tradesmen. Even in the famous court scene of Act IV scene 1, Shylock clearly is not pleading his case in front of an impartial Duke. Let us remember that the Duke himself describes Shylock as "A stony adversary, an inhuman wretch / Uncapable of pity, void and empty / From any dram of mercy." Social clashes are evident through the obvious prejudice that exists in this society against Jews, who are clearly treated in a terrible way by all concerned.