The treaty, currently negotiated between the US and the EU, is aimed at abolishing trade tariffs between the world's two biggest economic blocs.
About one fifth of jobs in Lithuania are dependent on exports. The opening up of the US market for the country's exporters would create even more jobs, Malmstrom said.
She said however, that there are no guarantees that the agreement would boost the annual income of an average European household by €500, as some studies have suggested.
EU and US negotiators want to finalize the deal by the end of this year.
The opposition to TTIP comes from groups concerned about it lowering environmental standards and consumer protection. A particularly controversial clause in the agreement would allow companies to sue governments if their decision endanger their profit plans.