In the 90s, the status of Crimea was an internal dispute in the newly-formed Ukrainian state. The status of Crimea as a part of the new Ukrainian state at this time was not yet settled in any way. The territory only became firmly a part of Ukraine in 1995.
The 2003 dispute over the island of Tuzla - whose status had not been clearly settled during the independence of Ukraine from the USSR - was settled diplomatically. If you call this occasion an "attempt to annex Ukraine", then we could equally say that "Romania attempted to annex Ukraine" when the countries had several rounds of negotiation and arbitration for control of Snake Island in the Black Sea.