felipe2k2:
It seems to me that the nature of IPSec VPN tunnels are that if Site A has traffic for Site B, the firewall at Site A is going to try to establish a tunnel with Site B to pass that traffic across.
If you are at Site B (with pfSense) and you disable the Phase 2's and Phase 1 for the tunnel to Site A (that has the Cisco ASA), no traffic will be able to pass from Site A to Site B, which is the goal.
Site A (which you have stated you do not have access to) is going to continue to try to establish a tunnel to Site B as it has traffic. As long as the tunnel config at Site B is disabled, though, you have nothing to worry about.
If the traffic from Site A is bothering you, you might consider creating a Block rule on the firewall where the source is Site A's IP address and the Destination is your WAN address. You can set the protocol to Any and block all the traffic, not just the IPSec traffic.
Hope this helps!