Tesla Inc. has plenty of options for raising money, but it is getting more expensive to do so.

The electric car maker signaled last week it could issue new debt or equity financing in the wake of a first-quarter loss that was much worse than Wall Street analysts expected. Elon Musk, on an earnings call Wednesday, said “there’s merit to the idea of raising capital at this point”—a reversal from the chief executive’s previous insistence the firm didn’t need more money.

Some...