I recommend networking with other parishioners – perhaps at the coffee-and-doughnut klatsches many parishes hold after Mass – to find out if others are bothered by the noise before Mass. If you can find a number of people who are also upset by the inability to pray quietly before Mass, then you can suggest that you meet as a group with the pastor to explain your concerns that there is no opportunity for personal prayer and recollection before Mass and that the church is being treated as a social hall rather than as a sanctuary.
Ideas for venues in which the pastor can address the problem to the parish might include the homily, the church bulletin, pastoral letters to parishioners, signs in the vestibule, and notes taped to the missalettes. In venues such as the homily and a pastoral letter, the pastor can outline the case for silence before Mass; in the other venues, a request for silence can be posted.