How to persuade my advisor to keep working with me even if my grades are poor?

So I am an international grad student in ECE in USA, in the field of Wireless Communications, and I am on my 2nd semester of my Master's program.

Last week I talked with my advisor and he told me he was unhappy about the grades I got last semester. More specifically, I took 2 courses and took B+ and A-. On the first course I thought I had scored A or more but I got a bad score on the final something I wasnt expecting. On the second one, I had a panic attack during the final and I couldn't think calmly, so I got a score for 60, when having 90+ on midterms. I told this to my advisor, and also told him that being away from home also made it harder for me psychologically, and he told me that many people have problems on the first semester, but he also said that if I don't correct my grades this semester it may mean that I am not suitable for doing research in this field, and that I would need to search for another research group, or leave with a master's and work at industry.

Note that my grades are over the department minimum for PhD entry. So it's my advisor's idea, not a department requirement.

So what should I do? Of course I will try my best to be improve this semester but I think I need to have a plan B in case my grades don't improve too much. What should I do to persuade my advisor?