Array of interfaces in SV

You can forward the whole array to the sub-module like this:

interface iface();
    logic a;
    logic b;
    modport mport(input a, output b);
endinterface
module submod (
    iface.mport iface_array 
);
    ...
endmodule
module mod (
    iface.mport iface_array 
);
    submod submod_inst(.iface_array(iface_array));
endmodule
module top ();
    iface top_iface_array  ();
    mod mod_inst(.iface_array(top_iface_array));
endmodule

interface iface();
    logic a;
    logic b;
    modport mport(input a, output b);
endinterface
module submod (
    iface.mport iface_port
);
    ...
endmodule
module mod (
    iface.mport iface_array 
);
    genvar i;
    generate
        for(i=0; i<4; i++) begin : submod_lp
            submod submod_inst(.iface_port(iface_array));
        end
    endgenerate
endmodule
module top ();
    iface top_iface_array  ();
    mod mod_inst(.iface_array(top_iface_array));
endmodule